#include <stdio.h>

int main(){
	FILE *fin,*fout;
	long int P,k;
	long int N,aux;
	
	fin=fopen("fact.in","rt");
	fout=fopen("fact.out","wt");
	
	fscanf(fin,"%ld",&P);
	
	if (P==0){
		N=1;
		fprintf(fout,"%ld",N);
		fclose(fin);
		fclose(fout);
		return 0;
	}
	

	N=P*5;
	
	while(N){
		k=N;
		aux=0;
		while (k>=5){
			k/=5;
			aux++;
		}
		
		
		
		if ((aux+N/5-1)==P){
			
			fprintf(fout,"%ld",N);
			fclose(fin);
			fclose(fout);
			return 0;
			
		}
		
		N-=5;
		
			
	}
	
	
	return 0;
}