import sys
input = sys.stdin.readline

N, M = map(int, input().split())
t, p = 0, 0

for _ in range(M):
    T, P = map(int, input().split())
    
    if abs(P-p)>T-t:
        print('No')
        break
    
    t, p = T, P
else:
    print('Yes')