N = int(input())
a = [int(input()) for i in range(7)]
m = 1001
minpr = 1000001
R = minpr
for i in range(7,N):
    x = int(input())
    b = a[i % 7]
    if b < m and b % 2 == 0:
        m = b
    if m * x < minpr and (m * x) % 2 == 0:
        minpr = m * x
    a[i % 7] = x
if minpr != R:
    print(minpr)
else:
    print(-1)