def numar_cifre_zero(n):
    count =  0
    while n >  0:
        n //=  5
        count += n
    return count

def gaseste_N(P):
    N =  0
    while numar_cifre_zero(N) < P:
        N +=  1
    return N if numar_cifre_zero(N) == P else -1

# Citirea datelor din fact.in
with open('fact.in', 'r') as fin:
    P = int(fin.readline())

# Calcularea lui N
N = gaseste_N(P)

# Scrierea rezultatului in fact.out
with open('fact.out', 'w') as fout:
    fout.write(str(N))