#include <iostream>
#include <fstream>

using namespace std;

int number_of_zeros(int number) {
    int zeros = 0;
    while (number / 5) {
        zeros += number / 5;
        number /= 5;
    }
    // cout << "zeros: " << zeros << endl;
    return zeros;
}

int binary_search(int left, int right, int p) {
    int middle;
    int zeros;
    while (left < right) {
        middle = right - (right - left) / 2;
        zeros = number_of_zeros(middle);
        if (zeros > p) {
            right = middle - 1;
        }
        if (zeros < p) {
            left = middle + 1;
        }
        if (zeros == p) {
            return middle;
        }
    }
    return -1;
}

int main() {
    int left = 0;
    int right = 100000000;
    int p;
    int number;
    ifstream input;
    ofstream output;

    input.open("fact.in");
    input >> p;
    input.close();

    if (p == 0) {
        number = 1; 
    } else {
        number = binary_search(left, right, p);
        if (number != -1) {
           for (; number_of_zeros(number) == p; --number); 
           ++number;
        }
    }

    output.open("fact.out");
    output << number;
    output.close();
    return 0;
}