import sys
input = sys.stdin.readline

# from collections import deque

def linput(ty=int, cnv=list):
    return cnv(map(ty, input().split()))

def vinput(rep=1, ty=int, cnv=list):
    return cnv(ty(input().rstrip()) for _ in "*"*rep)

def gcd(n,m):
    while m: n,m = m, n%m
    return n

def lcm(n,m): return n*m//gcd(n,m)

def main():
    N,M = linput()
    x = 0
    t = 0
    res = 1

    for _ in range(M):
        T,P = linput()
        if abs(P-x) > T-t:
            res = 0
            break
        x,t = P,T

    sT = "No Yes".split()
    print(sT[res])
    # for vR in mR:
    #     print(*vR, sep="")

if __name__ == "__main__":
    main()