N = int(input())

birthday = []
for i in range(N):
    A, B = map(int, input().split())
    birthday.append((A,B))

status = False
for i in range(N):
    for j in range(i+1, N):
        if birthday[i] == birthday[j]:
            # print(i,j)
            status = True
            break

if status:
    print("Yes")
else:
    print("No")