#include <bits/stdc++.h>
using namespace std;

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    
    int T; cin >> T;
    while(T--){
        int N,M; cin >> N >> M;
        vector<pair<int,int>> P(M);
        for(auto &[a,b] : P) cin >> a >> b,a--;

        bool yes = true;
        long long left = 0,right = 0;
        for(int i=0; i<M; i++){
            auto [p1,ign] = P.at((i-1+M)%M);
            auto [p2,a] = P.at(i);
            if(i == 0) p1 -= N;
            long long d = p2-p1;
            long long L = p1+a,R = p2-1+a;
            if(d > a) L = p2;
            if(i == 0) left = L,right = R;
            else{
                L -= a,R -= a;
                L = max(L,left),R = min(R,right);
                if(L > R){yes = false; break;}
                L += a,R += a;
                left = L,right = R;
            } 

        }

        if(yes) cout << "Yes\n";
        else cout << "No\n";
    }
}