N=int(input())
A=list(map(int,input().split()))
flag = False
for i in range(N-1):
    A[i],A[i+1] = A[i+1],A[i]
    for j in range(max(0,i-5),min(N-1,i+5)):
        if A[j] == A[j+1]:
            flag = True
    A[i],A[i+1] = A[i+1],A[i]
if flag:
    print("Yes")
else:
    print("No")