# https://yukicoder.me/problems/no/3576

from collections import deque

def main():
    N = int(input())
    st = []
    for _ in range(N):
        s, t = map(int, input().split())
        st.append((s, t))
    
    s_map = {}
    for s, t in st:
        if s not in s_map:
            s_map[s] = set()
        s_map[s].add(t)
    
    is_ok = True
    for value_set in s_map.values():
        if len(value_set) != 1:
            is_ok = False
    
    if is_ok:
        print("Yes")
    else:
        print("No")





if __name__ == "__main__":
    main()