#include <bits/stdc++.h>
using namespace std;

long long safemod(long long a,long long m){
    a %= m; a += m;
    return a>=m?a-m:a;
}
long long floor(long long a,long long b){
    if(b < 0) a *= -1,b *= -1;
    return a<0?(a+1)/b-1:a/b; 
}
long long ceil(long long a,long long b){
    if(b < 0) a *= -1,b *= -1;
    return a>0?(a-1)/b+1:a/b; 
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int A,B; cin >> A >> B;
    int mul = floor(A,B);
    A -= abs(B)*mul;
    A %= abs(B);
    cout << A << endl;
}