#include <iostream>
#include <fstream>

using namespace std;


int Zeros(int f) {
    int result = 0;

    for (int divisor = 5; f/divisor > 0; divisor *= 5) {
	result += f/divisor;
    }
    
    return result;
}

int main(int argc, char *argv[])
{
    int p;
    ifstream myfile;
    myfile.open("fact.in");
    myfile >> p;
    myfile.close();

    int result = 0;

    int zeros = 0;
    while (zeros < p) {
	result += 5;
	zeros = Zeros(result);
	if (Zeros(result) > p) result = -1;
    }

    if (result == 0) result = 1;
    
    ofstream outfile;
    outfile.open("fact.out");
    outfile << result;
    outfile.close();
    
    return 0;
}