#include <iostream>

using namespace std;

int main()
{
    using ll = long long;
    
    ll N, M;
    cin >> N >> M;

    if (M * 1000 > N) {
        cout << 0 << endl;
        return 0;
    }
    
    ll l = 1000, r = N;
    while (r - l > 1) {
        ll mid = (l + r) / 2;
        if (mid * M < N) {
            l = mid;
        } else {
            r = mid;
        }
    }
    
    for (; ; r--) {
        if (r % 1000 == 0) {
            cout << r << endl;
            break;
        }
    }
        
    return 0;
}