C :

#include <stdio.h>

int main(void) {
	int a, b = 0, c;
	scanf("%d", &a);
	while(b == 0)
		scanf("%d", &b);
	c = a % b;
	printf("%d", c);
	return 0;
}

C++ :

#include<cstdio>
using namespace std;
int main()
{
	int a,b,s;
	scanf("%d%d",&a,&b);
	s=a%b;
	printf("%d\n",s);
	return 0;
}

Pascal :

program yucong;
var
a,b,s:integer;
begin
read(a,b);
s:=a mod b;
writeln(s);
readln;
end.