#include <bits/stdc++.h>
using namespace std;
#define cs const
#define pb push_back
using pi = pair <int, int> ;

cs int oo = 1e9 + 7; 

void cmn(int & x, int y) {
    if(x > y) x = y; 
}
void cmx(int & x, int y) {
    if(x < y) x = y; 
}

cs int N = 1e6 + 5; 

int T, n, m; 
struct opt {
    int op, l, r, h;
} q[N];
int ans[N];

namespace zkw {
    int o[1 << 21], L;
    void upt(int x) {
        o[x] = max(o[x << 1], o[x << 1 | 1]);
    }
    void init(int n) {
        L = 2 << std :: __lg(n + 1);
        for(int i = 1; i <= n; i++) o[i + L] = - oo; 
        for(int i = L; i >= 1; i--) upt(i);
    }
    void ins(int x, int v) {
        for(cmx(o[x += L], v); x >>= 1; upt(x)); 
    }
    void clr(int x) {
        for(o[x += L] = -oo; x >>= 1; o[x] = -oo);
    }
    int qmx(int l, int r) {
        l += L - 1, r += L + 1; 
        // cerr << "FFFFF " << l << ' ' << r << endl;
        int ans = -oo; 
        for(; l ^ r ^ 1; l >>= 1, r >>= 1) {
            if((l & 1) == 0) cmx(ans, o[l ^ 1]);
            if((r & 1) == 1) cmx(ans, o[r ^ 1]);
        }
        return ans; 
    }
}
void work(int l, int r) {
    if(l == r) return;


    int mid = (l + r) >> 1; 
    vector <opt> S; 
    for(int i = l; i <= mid; i++) {
        if(q[i].op == 0) {
            S.pb(q[i]);
        }
    }
    for(int i = mid + 1; i <= r; i++) {
        if(q[i].op) {
            S.pb(q[i]);
        }
    }
    sort(S.begin(), S.end(), 
    []( cs opt & a, cs opt & b) {
        return a.h < b.h;
    });
    
    // cerr << "work " << l <<' ' << r << endl;
    for(auto [op, l, r, h] : S) {
        if(op == 0) {
            // cout << "ins " << l << ' ' << h << endl;
            zkw :: ins(l, h);
        }
        else {
            int c = zkw :: qmx(l, r);
            if(c != -oo) 
            cmn(ans[op], h - c);
        }
    }
    for(auto & c : S) {
        if(c.op == 0) {
            zkw :: clr(c.l);
        }
        c.h = - c.h; 
    }
    reverse(S.begin(), S.end());
    for(auto [op, l, r, h] : S) {
        if(op == 0) {
            // cerr << "ins " << l << " " << h << endl;
            zkw :: ins(l, h);
        }
        else {
            // cout << "qmx " << l << ' ' << r << ' ' << h << ' ' << zkw :: qmx(l, r) << endl;
            int c = zkw :: qmx(l, r);
            if(c != -oo) 
            cmn(ans[op], h - c);
        }
    }
    for(auto & c : S) {
        if(c.op == 0) {
            zkw :: clr(c.l);
        }
    }
    S.clear();

    work(l, mid);
    work(mid + 1, r);
}
void Main() {
    cin >> n >> m; 
    zkw :: init(n);
    for(int i = 1; i <= m; i++) {
        int o, x, h, l, r;
        cin >> o; 
        if(o == 0) {
            cin >> x >> h; 
            q[i] = (opt) {0, x, x, h}; 
        }
        if(o == 1) {
            cin >> l >> r >> h; 
            q[i] = (opt) {i, l, r, h};
            ans[i] = oo; 
        }
    }
    work(1, m); 
    for(int i = 1; i <= m; i++) if(q[i].op) {
        cout << (ans[q[i].op] == oo ? -1 : ans[q[i].op]) << '\n';
    }
}
int main() {
    #ifdef zqj
    freopen("1.in","r",stdin);
    #endif
    ios :: sync_with_stdio(0), cin.tie(0);
    cin >> T; 
    while(T--) Main();
    return 0; 
}