#include <iostream>

void solve(){
	using namespace std;
	int A, B;
	cin >> A >> B;
	int r = 1e8;
	for (int i = -200; i < 201; i++){
		if (A-B*i >= 0) r = min(r, A-B*i);
	}
	cout << r <<endl;
}

int main(){
	solve();
	return 0;
}