#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
using namespace std;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 1000000000000000001

int main(){
	
	long long a,b;
	cin>>a>>b;
	if(b<0){
		b *= -1;
	}
	long long ans = a%b;
	if(ans<0) ans+=b;
	cout<<ans<<endl;
	
	return 0;
}