#include<bits/stdc++.h>
using namespace std;
using Int = long long;
template<typename T1,typename T2> inline void chmin(T1 &a,T2 b){if(a>b) a=b;}
template<typename T1,typename T2> inline void chmax(T1 &a,T2 b){if(a<b) a=b;}

//INSERT ABOVE HERE
signed main(){
  Int h,a,d;
  cin>>h>>a>>d;
  vector<double> dp(h+1,0);
  for(Int i=1;i<=h;i++){
    Int x=max(0LL,i-a);
    Int y=max(0LL,i-d);
    dp[i]=min(dp[x]+1.0,dp[y]+1.5);      
  }
  cout<<dp[h]<<endl;
  return 0;
}