#include<bits/stdc++.h>
#define REP(i,n) for(int i=0,i##_len=int(n);i<i##_len;++i)
#define rep(i,a,b) for(int i=int(a);i<int(b);++i)
#define All(x) (x).begin(),(x).end()
#define rAll(x) (x).rbegin(),(x).rend()
using namespace std;
using ll = long long;

int main(){
    double t,s,d;
    cin>>t>>s>>d;
    double t_end = t + d/s;
    double res = 0.0;
    cerr << t_end << endl;
    #if 0
    while(t_end > 24) {
        // t を24時まで進める
        res += max(24.0 - max(t, 18.0), 0.0) + max(0.0, 6.0 - max(t, 0.0));
        t_end -= 24;
        t = 0;
    }
    res += max(t_end - max(t, 18.0), 0.0) + max(0.0, min(6.0, t_end) - max(t, 0.0)); 
    #endif 
    printf("%.9f", t_end - t);
}