#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef string str;
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
    ll n, k;
    cin >> n >> k;
    ll p = n / 1000;
    if (p < k) cout << 0;
    else
    {
        ll p2 = p % k;
        ll p3 = (p - p2) / k;
        cout << 1000 * p3;
    }
    return 0;
}