#include <stdio.h>
#include <stdlib.h>

int main(void) {
    long long N;
    int M;
    long a, x; // able, X
    scanf("%lld%d", &N, &M);
    
    a = N / 1000;
    x = (a / M) * 1000;
    printf("%ld\n", x);
    return EXIT_SUCCESS;
}