N, M = map(int, input().split())
T = [0]
P = [0]

for i in range(M):
    T_add, P_add = map(int, input().split())
    T.append(T_add)
    P.append(P_add)

P_now = 0
ans = 'Yes'
for i in range(M):
    if abs(P[i]-P[i-1]) > (T[i]-T[i-1]):
        ans = 'No'
        break
print(ans)