#include <fstream>

using namespace std;
ifstream in("fact.in");
ofstream out("fact.out");

int main()
{
    int n,i,j,S,sol;
    sol=0;
    in>>n;
    if(n==0)
        out<<1;
        else
        {
        for(i=5; i<=1000; i=i+5)
            {
                S=0;
                for(j=5; j<=i; j=j*5)
                {
                    S=S+i/j;
                    if(S==n)
                        sol=i;
                }
            if(sol!=0)
                break;
            }
        out<<sol;
        }
}