573 - The Snail, uva

#include<iostream>
#include<cstdio>
#include<cmath>
#define db(a) cout << #a << " = " << a << endl;
using namespace std;
int main(){
	double h, d, u, f;
	int days = 0;
	while(cin >> h >> u >> d >> f && h != 0){
		days = 0;
		double climbed = 0;
		double fac = (f * u) / 100.;
		while(true){
			days++;
			if(u >= 0) climbed += u;
			u -= fac;
			if(climbed > h) break;
			climbed -= d;
			if(climbed < 0) break;
		}
		if(climbed > h) printf("success on day %d\n", days);
		else printf("failure on day %d\n", days);
	}
	return 0;
}