/*Se da un numar intreg P. Sa se gaseasca cel mai mic numar natural strict pozitiv N 
pentru care N! are exact P cifre de 0 la sfarsit.*/

#include<stdio.h>
#define N 410000000
int main()   
{   
    int p,n,d,t,i,a=1;
	FILE *f1,*f2;   
    f1=fopen("fact.in","r");   
    f2=fopen("fact.out","w");   
    fscanf(f1,"%d",&p);   
    i=0;  
    t=0;   
    if(p==0){   
		fprintf(f2,"%d",1);   
        return 0;   
	}   
	for(i=5;i<=N;i=i+5) 
    {     
		d=1; 
		n=i/5;   
		while(n%5==0)   
		{
			d=d+1;
			n=n/5;
		}
		if(i==99999995)	
		{a++;}
		t=t+d;
		if(t>=p)
			break;
    }

	if(t>p && d>1)	fprintf(f2,"%d",0);
    else if(t==p)	fprintf(f2,"%d",i);   
    fclose(f1);   
    fclose(f2);   
    return 0;   
}