#include <fstream>

using namespace std;

const int L=28;
ifstream in("fact.in");
ofstream out("fact.out");

int nrzero(int n){
    int nr=0;
    while(n>=5){
        nr+=n/5;
        n/=5;
    }
    return nr;
}
int main(){
    int r=0, pas=1<<L, p;
    in>>p;
    while(pas!=0){
        if(nrzero(r+pas)<p){
            r+=pas;
        }
        pas/=2;
    }
    r++;
    if(nrzero(r)!=p){
        r=-1;
    }
    out<<r;
    return 0;
}