#pragma region template #include using namespace std; using ll = long long; using ull = unsigned long long; using ld = long double; using vi = vector; using vvi = vector; using vvvi = vector; using vll = vector; using vvll = vector; using vvvll = vector; using vld = vector; using vvld = vector; using vvvld = vector; using vs = vector; using pll = pair; using vp = vector; template using pqrev = priority_queue, greater>; #define rep(i, n) for (ll i = 0, i##_end = (n); i < i##_end; i++) #define repb(i, n) for (ll i = (n)-1; i >= 0; i--) #define repr(i, a, b) for (ll i = (a), i##_end = (b); i < i##_end; i++) #define reprb(i, a, b) for (ll i = (b)-1, i##_end = (a); i >= i##_end; i--) #define ALL(a) (a).begin(), (a).end() #define SZ(x) ((ll)(x).size()) //* constexpr ll MOD = 1e9 + 7; /*/ constexpr ll MOD = 998244353; //*/ constexpr ll INF = 1e+18; constexpr ld EPS = 1e-12L; constexpr ld PI = 3.14159265358979323846L; constexpr ll GCD(ll a, ll b) { return b ? GCD(b, a % b) : a; } constexpr ll LCM(ll a, ll b) { return a / GCD(a, b) * b; } template constexpr bool chmax(S &a, const T &b) { if (a < b) { a = b; return 1; } return 0; } template constexpr bool chmin(S &a, const T &b) { if (b < a) { a = b; return 1; } return 0; } #ifdef OJ_LOCAL #include "dump.hpp" #else #define dump(...) ((void)0) #endif template bool print_(const T &a) { cout << a; return true; } template bool print_(const vector &vec) { for (auto &a : vec) { cout << a; if (&a != &vec.back()) { cout << " "; } } return false; } template bool print_(const vector> &vv) { for (auto &v : vv) { for (auto &a : v) { cout << a; if (&a != &v.back()) { cout << " "; } } if (&v != &vv.back()) { cout << "\n"; } } return false; } void print() { cout << "\n"; } template void print(Head &&head, Tail &&... tail) { bool f = print_(head); if (sizeof...(tail) != 0) { cout << (f ? " " : "\n"); } print(forward(tail)...); } #pragma endregion void Pr(bool f){ cout << (f ? "Yes" : "No") << "\n"; exit(0); } int main() { cin.tie(0); ios::sync_with_stdio(false); cout << fixed << setprecision(20); ll n, m; cin >> n >> m; ll cur = 0; ll t = 0; rep(i, m){ ll a, b; cin >> a >> b; if(!(abs(cur-b)<=a-t)) Pr(0); t = a; } Pr(1); }