1

def main():
    data = []
    n = int(input())
    max_proizv = 0
    for i in range(n):
        data.append(int(input()))
    for i in range(0, n-1):
        for j in range(i+1, n):
            if data[i] != data[j]:
                sum = data[i] + data[j]
                proizv = data[i] * data[j]
                if sum % 2 != 0 and proizv % 5 == 0 and proizv > max_proizv:
                    max_proizv = proizv
    print(max_proizv)

main()