#include <stdio.h>

int zero(int a){
    int n = 0;
    while(a>=5){
	n+=(a/=5);
    }
    return n;
}




int main(){
    freopen("fact.in", "r", stdin);
    freopen("fact.out", "w", stdout);
    int n, i, pas = (1 << 30), r = 0;
    scanf("%d", &n);
    while(pas!=0){
	if(zero(pas+r) < n)
	    r+=pas;
	pas/=2;
    }
    if(zero(r+1+pas)!= n)
	printf("-1");
    else 
	printf("%d", r + 1);


}