#include <vector>
#include <set>
#include <iostream>

using namespace std;
using ll = int;
const ll inf = -1e9;
struct X {
	set<ll> vals;
};

ll closest(ll x, set<ll> &a) {
	auto u = a.upper_bound(x);
	auto l = a.lower_bound(x);
	ll ans = -inf;
	if (u != a.begin()) 
		ans = *prev(u);
	if (l != a.end()) 
		if (abs(ans-x) > abs(*l-x)) ans = *l;
	return ans;
}

ll closest(ll x, ll y, ll z) {
	if (abs(x-y) < abs(x-z)) return y;
	else return z;
}

struct Segtree {
    ll n;
    vector<X> tree;
    Segtree(ll n): n(n), tree(4*n) {
    }

    void insert(ll idx, ll val, ll cl = 0, ll cr = -1, ll k = 1) {
        if (cr == -1) cr = n;
				tree[k].vals.insert(val);
				if (cl == cr-1) return;
        ll mid = (cl+cr)/2;
        if (idx < mid) insert(idx, val, cl, mid, k*2);
        else insert(idx, val, mid, cr, k*2+1);
    }

    ll act(ll l, ll r, ll targ, ll cl = 0, ll cr = -1, ll k = 1) {
        if (cr == -1) cr = n;
        if (cr <= l || r <= cl) return -inf;
        if (l <= cl && r >= cr) {
					return closest(targ, tree[k].vals);
        }
        ll mid = (cl+cr)/2;
				ll a = act(l, r, targ, cl, mid, k*2);
				ll b = act(l, r, targ, mid, cr, k*2+1);
        return closest(targ, a, b);
    }
};

void solve() {
	int n, m; cin >> n >> m;
	Segtree s(n);
	for (int i = 0; i < m; i++) {
		ll type; cin >> type;
		if (type == 0) {
			ll x, h; cin >> x>> h;
			s.insert(x-1, h);
		}
		else {
			ll l, r, h; cin >> l >> r >> h;
			l--;
			ll ans = s.act(l, r, h);
			if (ans == -inf) cout << -1 << endl;
			else cout << abs(ans-h) << endl;
		}
	}

}

int main() {
	int t; cin >> t;
	while (t--) solve();

}