#include "bits/stdc++.h"
using namespace std;
int main(){
    int a,b;
    cin>>a>>b;
    cout<<a%b;
    return 0;
}

#define _CRT_SECURE_NO_WARNINGS #include<stdio.h> int main() { int x,y; scanf("%d %d", &x,&y); if (y>0&&x<1000&&y<x) { printf("%d",x%y ); }return 0; }

#include <stdio.h>
int main()
{
    int a,b;
    scanf("%d%d",&a,&b);
    printf("%d",a%b);
    return 0;
}
///B站搜索关注Siglota喵

#include <stdio.h>
int main()
{
    int x,y,f;
    scanf("%d%d\t",&x,&y);
    f=x%y;
    printf("%d",f);
    return 0;
}

#include<stdio.h>
int main()
{
    int x,y,z;
    scanf("%d %d",&x,&y);
    z=x%y;
    printf("%d",z);
    return 0;

}

#include<stdio.h>
int  main()
{
int x,y,z;
scanf("%d %d",&x,&y);


z=x%y;
printf("%d",z);
return 0;


}