不过从测试样例就可以de出来，不算太恶心
#include <iostream>

using namespace std;

int main() {
	double H,U,D,F;
	while(1){
		cin >> H >> U >> D >> F;
		if(H==0) break;
		F = U * F / 100;
		double h = 0.0;
		for(int i = 0; ; i++){
			h += (U - F * i > 0) ? (U - F * i) : 0;
			if(h > H){
				cout << "success on day " << (i+1) << endl;
				break;
			}
			h -= D;
			if(h < 0){
				cout << "failure on day " << (i+1) << endl;
				break;
			}
		}
	}
	return 0;
}