링크 : https://www.acmicpc.net/problem/1712
/*
문제 : 손익분기점
링크 : https://www.acmicpc.net/problem/1712
*/
#include <iostream>
#include <vector>
using namespace std;
int main() {
int A, B, C;
cin >> A >> B >> C;;
if(B >= C){
cout << -1;
return 0;
}
cout << A / (C - B) + 1;
return 0;
}