#include <stdio.h>

#include <stdlib.h>

int main()

{

    int dayTh;

    float Udis,currentHeight,firstClaim,HeightOfWell,downDis,fagtigue;

    while(scanf("%f %f %f %f",&HeightOfWell,&Udis,&downDis,&fagtigue)!=EOF){

        if(HeightOfWell==)

            break;

        currentHeight=;

        firstClaim=Udis;

        dayTh=;

        while(){

            currentHeight+=Udis;

            Udis-=fagtigue/*firstClaim;

            if(Udis<)

                Udis=;

            dayTh++;

            if(currentHeight>HeightOfWell){

                printf("success on day %d\n",dayTh);

                break;

            }

            else{

                currentHeight-=downDis;

                if(currentHeight<)

                    {

                        printf("failure on day %d\n",dayTh);

                        break;

                    }

                }

        }

    }

    return ;

}