def solve():
    N = int(input())
    names = []
    for _ in range(N):
        s, t = input().split()
        names.append((s, t))

    for i in range(N):
        s_i, t_i = names[i]
        
        s_can_use = True
        for j in range(N):
            if i == j: continue
            if s_i == names[j][0] or s_i == names[j][1]:
                s_can_use = False
                break
        
        t_can_use = True
        for j in range(N):
            if i == j: continue
            if t_i == names[j][0] or t_i == names[j][1]:
                t_can_use = False
                break
        
        if not s_can_use and not t_can_use:
            print("No")
            return
            
    print("Yes")

solve()