# What is two source code's difference?

#include <stdio.h>

int main()
{
int A,B,C;
scanf("%d %d %d",&A,&B,&C);
printf("%d\n",(A+B)%C);
printf("%d\n",(A%C)+(B%C)%C);
printf("%d\n",(AB)%C);
printf("%d\n",(A%C)
(B%C)%C);
return 0;
}

#include <stdio.h>

int main() {
int a, b, c;
scanf("%d %d %d", &a, &b, &c);
printf("%d\n", (a + b) % c);
printf("%d\n", (a % c + b % c) % c);
printf("%d\n", (a * b) % c);
printf("%d\n", (a % c * b % c) % c);
return 0;
}

Use of caps or not, placement of curly braces, grouping of round brackets.

“(AB)” is not “A times B”, in fact it is syntactically incorrect. To achieve multiply, you must use asterisk, i.e. “(A * B)”.