from collections import deque

def bfs(s):
    q = deque([])
    q.append((s, 1))
    
    while q:
        v, c = q.popleft()
        
        for nv in adj_list[v]:
            if color[nv]==-1:
                color[nv] = -c
                q.append((nv, color[nv]))
            else:
                if color[nv]==c:
                    return False
    
    return True

N, M = map(int, input().split())
LR = [tuple(map(int, input().split())) for _ in range(N)]
adj_list = [[] for _ in range(N)]

for i in range(N):
    Li, Ri = LR[i]
    
    for j in range(i+1, N):
        Lj, Rj = LR[j]
        a, b, c, d = Li, Ri, Lj, Rj
        
        if a>c:
            a, b, c, d = c, d, a, b
        
        if not b<c:
            flag1 = True
        else:
            flag1 = False
        
        Lj, Rj = M-1-Rj, M-1-Lj
        a, b, c, d = Li, Ri, Lj, Rj
        
        if a>c:
            a, b, c, d = c, d, a, b
        
        if not b<c:
            flag2 = True
        else:
            flag2 = False
            
        if flag1 and flag2:
            print('NO')
            exit()
        elif flag1 or flag2:
            adj_list[i].append(j)
            adj_list[j].append(i)

for i in range(N):
    color = [-1]*N
    
    if not bfs(i):
        print('NO')
        break
else:
    print('YES')