#include <bits/stdc++.h>

#define rep(i,s,n) for(int i = int(s); i < int(n); i++)
#define rrep(i,s,n) for(int i = int(n) - 1; i >= int(s); i--)
#define all(v) (v).begin(), (v).end()

using ll = long long;
using ull = unsigned long long;
using ld = long double;

bool chmin(auto &a, auto b) {
    if(a <= b) return false;
    a = b;
    return true;
}

bool chmax(auto &a, auto b) {
    if(a >= b) return false;
    a = b;
    return true;
}

void solve() {
    ll n,m;
    std::cin >> n >> m;
    std::vector<std::pair<ll,ll>> ab(m);
    for(auto &[a, b]: ab) {
        std::cin >> a >> b;
    }
    ll now = 0, i = 0;
    std::sort(all(ab));
    for(auto [a, b]: ab) {
        ll d = a - i;
        if(now + d == b || b <= d - 1) {
            i = a;
            now = b;
        }
        else {
            std::cout << "No\n";
            return;
        }
    }
    std::cout << "Yes\n";
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);
    int t;
    std::cin >> t;
    while(t--) {
        solve();
    }
}