#include <iostream>
#include <iomanip>
using namespace std;

int main() {
    int T, S, D;
    cin >> T >> S >> D;
    double time = (double)D / S;
    if (T + time >= 24) {
        cout << setprecision(15) << (24 - T) + (time - (24 - T)) * 1.5 << endl;
    } else {
        cout << setprecision(15) << time << endl;
    }
    return 0;
}