#include<cstdio>
using namespace std;
int main(){
	FILE*f=fopen("fact.in","r");
	FILE*g=fopen("fact.out","w");
	int r,nr,ok,x,k;
	long P,m,N;
	fscanf(f,"%d", &P);
	N=5*P;
	nr=0;
	x=5;
	r=P-1;
	k=5*(r);
	while (nr!=P){
	while(N/x!=0){
		nr=nr+N/x;
		x=x*5;
	}
	if(nr!=P){
		N=k;
		k=5*(r);
		r=r-1;
		nr=0;
		x=5;
	}
	}
	fprintf(g,"%d",N);
	fclose(f);
	fclose(g);
	}