#include <iostream>
#include <fstream>

using namespace std;

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

int main()
{
    bool OK = true;
    unsigned short _count = 0; long N, d;
    unsigned int P;
    f >> P;
    for(long i = 2; OK != false; i++)
    {
        _count = 0;
        for(long j = 1; j <= i; j++)
            if(j % 10 == 0)
            {
                d = j;
                while(d)
                {
                    if(d%10!=0) d = 0;
                    else _count++;
                    d /= 10;
                }
            }
            else
            {
                if(j % 5 == 0)
                {
                    d = j * (j-1);
                    while(d)
                    {
                        if(d%10!=0) d = 0;
                        else _count++;
                        d /= 10;
                    }
                }
            }
        
        if(_count == P) { N = i; OK = false; }
        else if(_count > P) { N = -1; OK = false; }
    }
    
    g << N;
}