#include<bits/stdc++.h> 
using namespace std;
int c[100005];
int main() {
    int a,b;
	cin>>a>>b;
	int n,s=0;
	for(int i=1;i<=a;i++) {
		for(int j=1;j<=b;j++) {
			n=i,b=j;
		    s+=1;
		    c[i]=s;
		}
		
	}
	n=a%b;
	cout<<n;
	return 0;
}