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

int main(){
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);

    int N,Q; cin >> N >> Q;
    vector<vector<int>> P(N);
    vector<tuple<int,int,int>> LRC(N);
    for(int i=0; i<N; i++){
        int l,r,c; cin >> l >> r >> c,l--;
        for(int p=l; p<r; p++) P.at(p).push_back(i);
        LRC.at(i) = {l,r,c};
    }

    vector<long long> one(N,-1);
    map<pair<int,int>,long long> memo;
    auto f = [&](auto f,int l,int r) -> long long {
        if(l >= r) return 0;
        if(l+1 == r){
            if(one.at(l) != -1) return one.at(l);
            int now = 0;
            for(auto pos : P.at(l)){
                auto [L,R,c] = LRC.at(pos);
                if(l == L && r == R) now = max(now,c);
            }
            return one.at(l) = now;
        }
        if(memo.count({l,r})) return memo[{l,r}];

        int m = (l+r)/2;

        long long ret = f(f,l,m)+f(f,m,r);
        for(auto pos : P.at(m)){
            auto [L,R,c] = LRC.at(pos);
            if(l <= L && L < m && m < R && R <= r) ret = max(ret,c+f(f,l,L)+f(f,R,r)); 
        }
        memo[{l,r}] = ret;
        return ret;
    };

    while(Q--){
        int a,b; cin >> a >> b,a--,b--;
        auto [l1,r1,c1] = LRC.at(a);
        auto [l2,r2,c2] = LRC.at(b);
        if(l1 > l2) swap(l1,l2),swap(r1,r2),swap(c1,c2);
        if(l2 < r1){cout << "-1\n"; continue;}


        cout << f(f,0,l1)+f(f,r1,l2)+f(f,r2,N)+c1+c2 << "\n";
    }
}