#include <stdio.h>

long long max_points(long long N) {
    long long lanterns = N / 500;
    long long banners = (N % 500) / 5;
    return (lanterns * 1000) + (banners * 5);
}

int main() {
    long long N;
    scanf("%lld", &N);
    printf("%lld\n", max_points(N));
    return 0;
}