#include <stdio.h>

int main(){
    long long int N, G, V, tmp2;
    long long int coin, tmp;

    scanf("%lld %lld %lld", &N, &G, &V);
    coin = N/5;
    tmp = coin*G/V;
    tmp2 = (coin*G)%V;

    printf("%lld.%lld\n", (coin*G)/V, tmp2*1000000000000/V);

    return 0;
}