diff --git a/du3/program.c b/du3/program.c
index 88d993a..e423d35 100644
--- a/du3/program.c
+++ b/du3/program.c
@@ -1,6 +1,112 @@
 #include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+float plus(float total, float number);
+float minus(float total, float number);
+float divided(float total, float number);
+float multiplied(float total, float number); 
+
 
 int main() {
+	char buffer[999];
+	char row[999];
+	char equation[999][20];
+	char output[999][10];
+	int output_length = 0;
+	int index = 0;
+	int eq_index = 0;
+	while (fgets(buffer, sizeof(buffer), stdin) != NULL) {
+		if (buffer[0] == '\n') break;
+		index = 0;
+		eq_index = 0;
+		int eq_operand_length = 0;
+		while (buffer[index] != '\n') {
+			if (buffer[index] != ' ') {
+				equation[eq_index][eq_operand_length] = buffer[index];
+				eq_operand_length++;
+			}
+			else {
+				equation[eq_index][eq_operand_length] = '\0';
+				eq_operand_length = 0;
+				eq_index++;
+			}
+			index++;
+		}
+		float total = 0.0;
+		int sign = 0;
+		char out[10] = "";
+		int n_of_signs = 0;
+		char operators[6] = "+-=*/";
+		char last_operator = '+';	
+		for (int i=0;i<eq_index+1;i++) {
+			n_of_signs = 0;
+			for (int l=0; l<5;l++) {
+				if (strchr(equation[i], operators[l]) != NULL) {
+					n_of_signs++;	
+				}
+			}	
+			if (((n_of_signs == 1) && sign && (strlen(equation[i]) == 1)) || ((n_of_signs == 0) && !sign)) {
+				if (!sign) {
+					switch (last_operator) {
+						case '+':
+							total = plus(total, atof(equation[i]));
+							break;
+						case '-':
+							total = minus(total, atof(equation[i]));
+							break;
+						case '*':
+							total = multiplied(total, atof(equation[i]));
+							break;
+						case '/':
+							total = divided(total, atof(equation[i]));
+							break;
+						case '=':
+							if (total == atof(equation[i])) {
+								strcpy(output[output_length], "OK");
+								output_length++;
+							}
+							else {
+								strcpy(output[output_length], "ZLE");
+								output_length++;
+							}
+							break;
+					} 
+				}
+				else {
+					last_operator = equation[i][0];
+				}			
+			}
+		       	else {
+				strcpy(output[output_length], "CHYBA");
+				output_length++;
+				break;
+			}
+			sign = !sign;	
+		}
+		//printf("%s\n",out);
+
+	}
+	for (int i=0; i<output_length; i++) {
+		printf("%s\n", output[i]);
+	}
 
 	return 0;
 }
+
+
+float plus(float total, float number) {
+	return total + number;
+}
+
+float minus(float total, float number) {
+	return total - number;
+}
+
+float divided(float total, float number) {
+	return total / number;
+}
+
+float multiplied(float total, float number) {
+	return total * number;
+}