import sys
from collections import deque
import bisect
import copy
import heapq
import itertools
import math
input = sys.stdin.readline
sys.setrecursionlimit(1000000)
mod = 10 ** 9 + 7

def read_values(): return map(int, input().split())
def read_index(): return map(lambda x: int(x) - 1, input().split())
def read_list(): return list(read_values())
def read_lists(N): return [read_list() for n in range(N)]


def main():
    N, M = read_values()
    p = 0
    t = 0

    for _ in range(M):
        T, P = read_values()
        if (T - t) < abs(P - p):
            print("No")
            return
        p = P
        t = T

    print("Yes")


if __name__ == "__main__":
    main()