#include<stdio.h>
void main()
{int n,p,k=0,i,P;
FILE *f=fopen("factorial.txt","r");
FILE *g=fopen("factorial.out","w");
fscanf(f,"%d",&p);
P=1;i=1;
while(k<p){P=P*i;
	   if((i%5==0)||(i%10==0)) k++;
	   i++;}
fprintf(g,"%d",i);
fclose(f);
fclose(g);
}