#include<stdio.h>

FILE *fin=fopen("fact.in","r");
FILE *fout=fopen("fact.out","w");

int save,n,i,q,k;

int main(){
	
	fscanf(fin,"%d",&n);
	
	q=0;
	
	if(n==0) fprintf(fout,"1");
	
	else{
		
		while(n){
			
			i+=5;
			save=i;
			while(save%5==0){
				save/=5;
				n--;
			}
			
		}
	}
	
	fprintf(fout,"%d",i);
	
	fclose(fin);
	fclose(fout);
	return 0;
	
}