import sys

sys.setrecursionlimit(10 ** 7)
input = sys.stdin.readline
f_inf = float('inf')
mod = 10 ** 9 + 7


def resolve():
    n, m = map(int, input().split())
    prev_p = 0
    prev_t = 0
    for _ in range(m):
        t, p = map(int, input().split())
        if abs(prev_p - p) > t - prev_t:
            print("No")
            break
        prev_p = p
        prev_t = t
    else:
        print("Yes")


if __name__ == '__main__':
    resolve()