#include 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; }