#include <cstdio>

using namespace std;

int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
    int n,i,j,htc=0,p,x=0;
    scanf("%d",&n);
    if (n==0) printf("1");
    else {for (i=1;htc<n;++i) {p=5*i;x=0; while(!(p%5)) {++htc;++x; p/=5;}
    }
    if (htc!=n) printf("-1");
    else    printf("%d\n",5*(i-1));}
    return 0;
}