import sys read = sys.stdin.buffer.read readline = sys.stdin.buffer.readline readlines = sys.stdin.buffer.readlines sys.setrecursionlimit(10 ** 7) from itertools import permutations def miller_rabin(n): # 確率的素数判定(ミラーラビン素数判定法) # 素数なら確実に True を返す、合成数なら確率的に False を返す # True が返ったなら恐らく素数で、False が返ったなら確実に合成数である # 参考: http://tjkendev.github.io/procon-library/python/prime/probabilistic.html # 検証: https://yukicoder.me/submissions/381948 primes = [2, 325, 9375, 28178, 450775, 9780504, 1795265022] # 32bit: [2, 7, 61] if n == 2: return True if n <= 1 or n & 1 == 0: return False d = m1 = n - 1 d //= d & -d for a in primes: if a >= n: return True t, y = d, pow(a, d, n) while t != m1 and y != 1 and y != m1: y = y * y % n t <<= 1 if y != m1 and t & 1 == 0: return False return True n = int(readline()) a = list(readline().rstrip().decode().split()) ans = 0 for aa in permutations(a): v = '' for ai in aa: v += ai v = int(v) if miller_rabin(v): ans = max(ans, v) print(ans if ans != 0 else -1)