#include <bits/stdc++.h>
using namespace std;
double dp[10001];
int main(){
  cin.tie(nullptr)->sync_with_stdio(false);
  int h, a, d; cin >> h >> a >> d;
  for(int i = 1; i <= h; ++i){
    dp[i] = 1 + (i >= a ? dp[i - a] : 0);
    dp[i] = min(dp[i], 1.5 + (i >= d ? dp[i - d] : 0));
  }
  cout << dp[h] << endl;
  return 0;
}