# Uses python3
   import sys
   input = sys.stdin.read()
   tokens = input.split()
   a = int(tokens[0])
   b = int(tokens[1])
   print(a + b)

# Uses python3
   n = int(input())
   a = [int(x) for x in input().split()]
   product = 0
   for i in range(n):
       for j in range(i + 1, n):
           product = max(product, a[i] * a[j])
   print(product)