#include <cstdio>

FILE *in,*out;

using namespace std;

const int L = 30;

int nrcifrezero(int x)
{
    int r = 0;
    while(x != 0) {
        r += x/5;
        x /= 5;
    }
    return r;

}

int cauta(int x)
{
    int pas,r = 0;
    pas = 1 << L;
    while(pas != 0) {
        if(nrcifrezero(r + pas) < x)
            r += pas;
        pas /= 2;
    }
    r ++;
    if(nrcifrezero(r) != x)
        return -1;
    return r;
}

int main()
{
    in = fopen("fact.in","r");
    out = fopen("fact.out","w");
    int p;
    fscanf(in,"%d",&p);
    if(p == 0)
        fprintf(out,"1");
    else
        fprintf(out,"%d",cauta(p));
    return 0;
}