n,m = map(int,input().split())
TP = [list(map(int,input().split())) for _ in range(m)]
T = 0
P = 0
for i in range(m):
    if TP[i][0] - T < abs(TP[i][1] - P):
        print("No")
        exit()
    else:
        T = TP[i][0]
        P = TP[i][1]
print("Yes")