diff --git a/du4/program.c b/du4/program.c
index 8b65b66..8477261 100644
--- a/du4/program.c
+++ b/du4/program.c
@@ -1,93 +1,91 @@
 #include <stdio.h>
-#include <stdlib.h>
 #include <string.h>
+#include <stdlib.h>
 #include <math.h>
 
-int Program() {
-    static void Main(string[] args) {
-        int ch = Console.Read();
-        string priklad = "";
-        int count = 0;
+int main() {
+    int ch = getchar();
+    char priklad[300];
+    int count = 0;
 
-        while (true) {
-            priklad += (char)ch;
-            if (ch == '\n') {
-                count++;
+    for (int idx = 0; 1; idx++) {
+        priklad[idx] = ch;
+        if (ch == '\n') {
+            count++;
+        }
+        ch = getchar();
+        if ((priklad[idx] == '\n' && ch == '\n') || ch == EOF) {
+            break;
+        }
+    }
+
+    char *start = priklad, *end = NULL;
+
+    for (int c = 0; c < count; c++) {
+        int skip = 0, z = 0;
+
+        for (int idx = 0; start[idx] != '\n'; idx++) {
+            if (start[idx] == '+' || start[idx] == '-' || start[idx] == '*' || start[idx] == '/') {
+                z = 1;
             }
-            ch = Console.Read();
-            if ((priklad[priklad.Length - 1] == '\n' && ch == '\n') || ch == -1) {
+            if ((start[idx] < '0' || start[idx] > '9') && start[idx] != ' ' && start[idx] != '=' && start[idx] != '+' && start[idx] != '-' && start[idx] != '*' && start[idx] != '/' && start[idx] != '.') {
+                skip = 1;
+                printf("CHYBA\n");
+                while ((*start) != '\n') {
+                    start++;
+                }
+                start++;
                 break;
             }
         }
 
-        string start = priklad;
-        string end = null;
+        if (skip == 1) {
+            continue;
+        }
+        if (z == 0) {
+            while ((*start) != '\n') {
+                start++;
+            }
+            start++;
+            printf("CHYBA\n");
+            continue;
+        }
+        float num1 = strtof(start, &end);
+        if (end == start) {
+            printf("KONIEC\n");
+        }
+        while ((*start) != '+' && (*start) != '-' && (*start) != '/' && (*start) != '*') {
+            start++;
+        }
+        char znak = (*start);
+        start++;
 
-        for (int c = 0; c < count; c++) {
-            int skip = 0, z = 0;
+        float num2 = strtof(start, &end);
+        start = end;
+        while (((*start) < '0' || (*start) > '9') && (*start) != '-') {
+            start++;
+        }
 
-            for (int idx = 0; start[idx] != '\n'; idx++) {
-                if (start[idx] == '+' || start[idx] == '-' || start[idx] == '*' || start[idx] == '/') {
-                    z = 1;
-                }
-                if ((start[idx] < '0' || start[idx] > '9') && start[idx] != ' ' && start[idx] != '=' && start[idx] != '+' && start[idx] != '-' && start[idx] != '*' && start[idx] != '/' && start[idx] != '.') {
-                    skip = 1;
-                    Console.WriteLine("CHYBA");
-                    while (start[0] != '\n') {
-                        start = start.Substring(1);
-                    }
-                    start = start.Substring(1);
-                    break;
-                }
-            }
+        float vysledok2 = strtof(start, &end);
+        start = end;
+        start++;
+        float vysledok = 0;
 
-            if (skip == 1) {
-                continue;
-            }
-            if (z == 0) {
-                while (start[0] != '\n') {
-                    start = start.Substring(1);
-                }
-                start = start.Substring(1);
-                Console.WriteLine("CHYBA");
-                continue;
-            }
-            float num1 = float.Parse(start, out end);
-            if (end == start) {
-                Console.WriteLine("KONIEC");
-            }
-            while (start[0] != '+' && start[0] != '-' && start[0] != '/' && start[0] != '*') {
-                start = start.Substring(1);
-            }
-            char znak = start[0];
-            start = start.Substring(1);
-
-            float num2 = float.Parse(start, out end);
-            start = end;
-            while ((start[0] < '0' || start[0] > '9') && start[0] != '-') {
-                start = start.Substring(1);
-            }
-
-            float vysledok2 = float.Parse(start, out end);
-            start = end;
-            start = start.Substring(1);
-            float vysledok = 0;
-
-            if (znak == '-') {
-                vysledok = num1 - num2;
-            } else if (znak == '+') {
-                vysledok = num1 + num2;
-            } else if (znak == '*') {
-                vysledok = num1 * num2;
-            } else if (znak == '/') {
-                vysledok = num1 / num2;
-            }
-            vysledok = (float)Math.Round(vysledok * 100) / 100;
-            if (Math.Abs(vysledok2 - vysledok) < 0.001) {
-                Console.WriteLine("OK");
-            } else {
-                Console.WriteLine("ZLE");
-            }
+        if (znak == '-') {
+            vysledok = num1 - num2;
+        } else if (znak == '+') {
+            vysledok = num1 + num2;
+        } else if (znak == '*') {
+            vysledok = num1 * num2;
+        } else if (znak == '/') {
+            vysledok = num1 / num2;
+        }
+        vysledok = (round(vysledok * 100)) / 100;
+        if (vysledok2 - vysledok < 0.001 && vysledok2 - vysledok > -0.001) {
+            printf("OK\n");
+        } else {
+            printf("ZLE\n");
         }
     }
-}
\ No newline at end of file
+    return EXIT_SUCCESS;
+}