/*   @JUDGE_ID:   1705PZ   573   C */
#include <stdio.h>

int main(){
float h,u,d,f,now,delta;
int day;
while(1){
	scanf("%f %f %f %f",&h,&u,&d,&f);
	if(h == 0)
		break;
	delta = u * f * 0.01;
	now = 0;
	day = 0;
	while(1){
		day++;
		now += u;
		if(now > h){
			printf("success on day %d\n",day);
			break;
			}
		now -= d;
		if(now < 0){
			printf("failure on day %d\n",day);
			break;
			}
		if(u - delta >= 0)
			u -= delta;
		else
			u = 0;
		}
	}
return 0;
}
@END_OF_SOURCE_CODE