# 写像判定


def main():

    N = int(input())
    ans = "Yes"
    f_dict = {}

    for _ in range(N):
        s,t = map(int, input().split())

        if str(s) in f_dict:
            if f_dict[str(s)] != t:
                ans = "No"
        else:
            f_dict[str(s)] = t

    print(ans)        


if __name__ == "__main__":
    main()