diff --git a/du3/program.c b/du3/program.c
new file mode 100644
index 0000000..03a167d
--- /dev/null
+++ b/du3/program.c
@@ -0,0 +1,107 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <assert.h>
+
+#define STACK_SIZE 10
+
+struct stack{
+    float values[STACK_SIZE];
+    int size;
+};
+
+void push_stack(struct stack *s, float value){
+    if (s->size >= STACK_SIZE){
+        printf("Chyba: zasobnik je plny!\n");
+        exit(1);
+}
+    s->values[s->size] = value;
+    s->size++;
+    }
+
+float pop_stack(struct stack *s){
+    if (s->size <= 0){
+        printf("Chyba: zasobnik je prazdny!\n");
+        exit(1);
+}
+    s->size--;
+    return s->values[s->size];
+    }
+
+void print_stack(struct stack *s){
+    for (int i = 0; i < s->size; i++){
+        printf("%.2f ", s->values[i]);
+        }
+    printf("\n");
+    }
+
+int main(){
+    struct stack s;
+    s.size = 0;
+
+    char input[100];
+
+    while (1){
+        if (scanf("%s", input) != 1){
+            printf("Chyba: nepodarilo sa nacitat vstup.\n");
+            return 1;
+            }
+
+        char *endptr;
+        float value = strtof(input, &endptr);
+
+            if (*endptr == '\0') {
+            push_stack(&s, value);
+            print_stack(&s);
+            } 
+        else if (strcmp(input, "+") == 0){
+            if (s.size < 2){
+                printf("Chyba: malo hodnot v zasobniku!\n");
+                return 1;
+                }
+            float b = pop_stack(&s);
+            float a = pop_stack(&s);
+            push_stack(&s, a + b);
+            print_stack(&s);
+            } 
+        else if (strcmp(input, "-") == 0){
+            if (s.size < 2){
+                printf("Chyba: malo hodnot v zasobniku!\n");
+                return 1;
+                }
+            float b = pop_stack(&s);
+            float a = pop_stack(&s);
+            push_stack(&s, a - b);
+            print_stack(&s);
+            } 
+        else if (strcmp(input, "*") == 0){
+            if (s.size < 2){
+                printf("Chyba: malo hodnot v zasobniku!\n");
+                return 1;
+                }
+            float b = pop_stack(&s);
+            float a = pop_stack(&s);
+            push_stack(&s, a * b);
+            print_stack(&s);
+            } 
+        else if (strcmp(input, "/") == 0){
+            if (s.size < 2){
+                printf("Chyba: malo hodnot v zasobniku!\n");
+                return 1;
+                }
+            float b = pop_stack(&s);
+            float a = pop_stack(&s);
+            if (b == 0){
+                printf("Chyba: delenie nulou!\n");
+                return 1;
+                }
+            push_stack(&s, a / b);
+            print_stack(&s);
+            } 
+        else{
+            printf("Chyba: neplatny vstup '%s'\n", input);
+            return 1;
+            }
+            }
+    return 0;
+}