UVa 573 - The Snail

// UVa 573 - The Snail

#include <iostream>
#include <math.h>
using namespace std;

int main() {
	int h, u, d, f;
	while (cin >> h >> u >> d >> f && (h != 0 || u != 0 || d != 0 || f != 0)) {
		int day = 0;
		bool out = false;
		double height = 0, ff = f / 100.0, ftg = 0;
		do {
			day++;
			// climb
			height += u - ftg * u;
			if (height > h) {
				out = true;
				break;
			}
			// slide
			height -= d;
			if (height < 0) {
				out = false;
				break;
			}
			// fatigue
			ftg += ff;
			if (ftg >= 1)
				ftg = 1;
		} while (height >= 0);
		if (out)
			cout << "success on day " << day << endl;
		else
			cout << "failure on day " << day << endl;
	}
	return 0;
}