#include <stdio.h> 
#include <stdlib.h> 
#include <string.h>
#include <math.h>  

int main()
{
	FILE* input = fopen("fact.in", "r"); 
	FILE* output = fopen("fact.out", "a"); 

	int p, i = 1; 
	fscanf(input, "%i", &p); 

	while(i != 0){
		int j = 1; 
		int k = 1;; 

		for(k = 1; k <= i; k++){
			j *= k; 
		}

		if(j % (int)pow(10,p) == 0 ){
			fprintf(output, "%i", i); 
			i = -1; 
		} 

		i++; 
	}

	fclose(input); 
	fclose(output); 
	return 0; 
}