n, m = map(int, input().split())
tp = [[0, 0]] + [list(map(int, input().split())) for i in range(m)]
ind = 0
for i in range(1, m+1):
    if tp[i][0] - tp[i-1][0] < tp[i][1] - tp[i-1][1]:
        print("No")
        exit()
print("Yes")