#include<bits/stdc++.h>
using namespace std;

#define REP(i,a,b) for(i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

#define mygc(c) (c)=getchar_unlocked()
#define mypc(c) putchar_unlocked(c)

void reader(int *x){int k,m=0;*x=0;for(;;){mygc(k);if(k=='-'){m=1;break;}if('0'<=k&&k<='9'){*x=k-'0';break;}}for(;;){mygc(k);if(k<'0'||k>'9')break;*x=(*x)*10+k-'0';}if(m)(*x)=-(*x);}
void reader(int *x, int *y, int *z){reader(x);reader(y);reader(z);}

int H, A, D;
double res[100000];

int main(){
  int i, j, k;

  reader(&H,&A,&D);
  res[0] = 0;
  REP(i,1,H+1){
    res[i] = min(1.0 + (i-A>=0?res[i-A]:0), 1.5 + (i-D>=0?res[i-D]:0));
  }

  printf("%.1f\n",res[H]);

  return 0;
}