#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < n; ++i)
using ll = long long;
using namespace std;
const int INF = 1e9;

int main() {
    int A, B, C;
    cin >> A >> B >> C;

    double ans = A / B * C + A%B*((double)C / B);
    printf("%.6f\n", ans);

    return 0;
}