#include<bits/stdc++.h>
using namespace std;
int main(){
    int h,a,d;cin >> h >> a >> d;
    vector<double> dp(h+1,1e9);
    dp[0]=0;
    for(int i=0;i<h;i++){
        int u=min(i+a,h),v=min(i+d,h);
        dp[u]=min(dp[u],dp[i]+1);
        dp[v]=min(dp[v],dp[i]+1.5);
    }
    cout << fixed << setprecision(5) << dp[h] << endl;
}