import sys
read = sys.stdin.buffer.read
readlines = sys.stdin.buffer.readlines
input = sys.stdin.buffer.readline
N, M = map(int, input().split())
time = curr = 0
for line in readlines():
    t, p = map(int, line.split())
    if t - time < abs(p - curr):
        print('No')
        break
    time, curr = t, p
else:
    print('Yes')