#include <fstream>

using namespace std;

ifstream f("fact.in");
ofstream g("fact.out");

int doi(int x){
    int z = 0;
    while(x % 2 == 0){
        x = x / 2;
        z++;
    }
    return z;
}

int cinci(int x){
    int z = 0;
    while(x % 5 == 0){
        x /= 5;
        z++;
    }
    return z;
}

int min1(int a,int b){
    if(a<b)
        return a;
    else return b;
}

int main(){
    int p,zero = 0,x = 0,nr_doi = 0,nr_cinci = 0;
    f>>p;
    if(p == 0)
        g<<1;
    else{
        while(zero<p){
            x++;
            nr_doi += doi(x);
            nr_cinci += cinci(x);
            zero = min1(nr_doi , nr_cinci);
        }
    }
    if(zero > p)
        g<< -1;
    else
        g<<x;
    return 0;
}