import random

with open("elmaj.in") as f:
    n = int(f.readline())
    v = list(map(int, f.readline().split()))
gasit = False
for _ in range(30):
    x = random.choice(v)
    cnt = v.count(x)
    if cnt >= n//2+1:
        with open("elmaj.out", "w") as g:
            g.write(f"{x}{cnt}")
        gasit = True
        break

if not gasit:
    with open("elmaj.out", "w") as g:
        g.write("-1")