N=int(input())
A=list(map(int,input().split()))
for i in range(N-1):
    B=A[:]
    B[i],B[i+1]=B[i+1],B[i]
    for j in range(i-1,min(N-1,i+3)):
        if B[j]==B[j+1]:exit(print("Yes"))
print("No")