#include <iostream>
#include <math.h>
#include <algorithm>
#include <functional>
#include <vector>
#include <typeinfo>
#include <climits>
#include <ctype.h>
#include <string>
using namespace std;
#define INIT cin.tie(0); ios::sync_with_stdio(false);
#define FOR(i, a, n) for (int i = a; i < n; i++)
#define REP(i, n) for(int i = 0; i < n; i++)

int main()
{
    INIT;

    int n, m;
    cin >> n >> m;

    int i = 1;
    int c = 0;
    while(1){
        int hoge = i * m * 1000;
        if(n > hoge){
            c = 1;
            n -= hoge;
            i++;
        }else break;
    }
    if(c = 1) cout << i * 1000 << endl;
    else cout << 0 << endl;

    return 0;
}