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

#define in "fact.in"
#define out "fact.out"

int main()
{
	FILE * fi = fopen(in, "r");
	FILE * fo = fopen(out, "w");

	unsigned long p, N;
	fscanf(fi, "%lu", &p);

	N = 0;

	long i, j;

	if(p==0)
		i = 1;
	else{
		for(i=5;N<p;i+=5){
			j = i;
			while(j%5==0){
				N++;
				j /= 5;
			}
		}
		i -= 5;
	}

	if(N!=p)i = -1;
	fprintf(fo, "%li", i);

	fclose(fi);
	fclose(fo);
	return 0;
}