n = int(input())
a = list(map(int, input().split()))

flag = False
for i in range(n - 1):
    b = a.copy()
    b[i], b[i + 1] = b[i + 1], b[i]
    
    for j in range(n - 1):
        if b[j] == b[j + 1]:
            flag = True
            
print("Yes" if flag else "No")