#include <fstream>

using namespace std;

int main()
{
    FILE*fin=fopen("factorial.in","r");
    FILE*fout=fopen("factorial.out","w");
    long long int p, k=0, f=0, z=0;
    fscanf(fin,"%lld",&p);
    while(k<p)
    {
        f+=5;
        z=f;
        while(z%5==0)
            ++k, z/=5;
    }
    if(k==p) fprintf(fout,"%lld",f);
    else fprintf(fout,"-1");
    return 0;
}