uva573 The Snail

#include<stdio.h>
#include<math.h>
#include<stdlib.h>
#include<string.h>

double H,U,D,F;

int main()
{
    while(scanf("%lf%lf%lf%lf",&H,&U,&D,&F)!=EOF&&H)
    {
        int flag=0;
        int day=0;
        double climbH=0;
        double reduce=U;
        while(1)
        {
            day++;
            climbH+=U;
            if(climbH > H)
            {
                flag = 1;
                break;
            }
            climbH -= D;
            if(climbH < 0)
                break;
            U-=F*reduce/100;
            if(U <= 0)
                U=0;
        }
        if (flag)  
            printf("success on day %d\n", day);  
        else  
            printf("failure on day %d\n", day);
    }
    return 0;
}