let n = readLine()!.split(separator: " ").map{Int($0)!}
var s = "Yes"
var (x,t) = (0,0)
for _ in 1...n[1]{
    let l = readLine()!.split(separator: " ").map{Int($0)!}
    if abs(l[1] - x) > abs(l[0] - t){
        s = "No"
    }
    (x,t) = (l[1],l[0])
}
print(s)