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

#define ll long long

int main() {
	ios::sync_with_stdio(false);
	cin.tie(nullptr);
	
	ll N, M;
	cin >> N >> M;
	
	if (N < M * 1000) {
		cout << "0" << "\n";
		return 0;
	}
	
	ll T;
	T = (N + M - 1) / M;
	
	for (int i = T; i >= 0; i--) {
		if (i * 1000 * M <= N) {
			cout << i * 1000 << "\n";
			break;
		}
	}
	
	return 0;
	
	
}