n = int(input())
a = list(map(int, input().split()))
for i in range(n-1):
    na = a.copy()
    na[i], na[i+1] = na[i+1], na[i]
    f = False
    for j in range(n-1):
        if na[j] == na[j+1]:
            f = True
            break
    if f:
        print("Yes")
        exit()
print("No")