#include <iostream>

using namespace std;

int main()
{
   int m;
   int d;
   int n;
   int x=0;
   int y=0;

   cin>>m;
   cin>>d;
   cin>>n;

   while(m >= x){
    x +=d;
       y+=1;
       if(x >= m){
           break;
       }
    x-=n;


   }

   cout<<y;
    return 0;
}