#include<bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include <debug.hpp>
#define debug(...) debug_print::multi_print(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) (static_cast<void>(0))
#endif
//#pragma GCC target("avx,avx2")
//#pragma GCC optimize("O3")
//#pragma GCC optimize("unroll-loops")
using ll = long long;
using ull = unsigned long long;
using ld = long double;
using pll = pair<ll,ll>;
using pii = pair<int,int>;
using vi = vector<int>;
using vvi = vector<vi>;
using vvvi = vector<vvi>;
using vl = vector<ll>;
using vvl = vector<vl>;
using vvvl = vector<vvl>;
using vul = vector<ull>;
using vpii = vector<pii>;
using vvpii = vector<vpii>;
using vpll = vector<pll>;
using vvpll = vector<vpll>;
using vs = vector<string>;
template<class T> using pq = priority_queue<T,vector<T>, greater<T>>;
#define overload4(_1, _2, _3, _4, name, ...) name
#define overload3(a,b,c,name,...) name
#define rep1(n) for (ll UNUSED_NUMBER = 0; UNUSED_NUMBER < (n); ++UNUSED_NUMBER)
#define rep2(i, n) for (ll i = 0; i < (n); ++i)
#define rep3(i, a, b) for (ll i = (a); i < (b); ++i)
#define rep4(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep1(n) for(ll i = (n) - 1;i >= 0;i--)
#define rrep2(i,n) for(ll i = (n) - 1;i >= 0;i--)
#define rrep3(i,a,b) for(ll i = (b) - 1;i >= (a);i--)
#define rrep4(i,a,b,c) for(ll i = (a) + (((b)-(a)-1) / (c) - (((b)-(a)-1) % (c) && (((b)-(a)-1) ^ c) < 0)) * (c);i >= (a);i -= c)
#define rrep(...) overload4(__VA_ARGS__, rrep4, rrep3, rrep2, rrep1)(__VA_ARGS__)
#define all1(i) begin(i) , end(i)
#define all2(i,a) begin(i) , begin(i) + a
#define all3(i,a,b) begin(i) + a , begin(i) + b
#define all(...) overload3(__VA_ARGS__, all3, all2, all1)(__VA_ARGS__)
#define sum(...) accumulate(all(__VA_ARGS__),0LL)
template<class T> bool chmin(T &a, const T &b){ if(a > b){ a = b; return 1; } else return 0; }
template<class T> bool chmax(T &a, const T &b){ if(a < b){ a = b; return 1; } else return 0; }
template<class T> auto min(const T& a){return *min_element(all(a));}
template<class T> auto max(const T& a){return *max_element(all(a));}
template<class... Ts> void in(Ts&... t);
#define INT(...) int __VA_ARGS__; in(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__; in(__VA_ARGS__)
#define STR(...) string __VA_ARGS__; in(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__; in(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__; in(__VA_ARGS__)
#define LD(...) ld __VA_ARGS__; in(__VA_ARGS__)
#define VEC(type, name, size) vector<type> name(size); in(name)
#define VV(type, name, h, w) vector<vector<type>> name(h, vector<type>(w)); in(name)
ll intpow(ll a, ll b){ll ans = 1; while(b){if(b & 1) ans *= a; a *= a; b /= 2;} return ans;}
ll modpow(ll a, ll b, ll p){ ll ans = 1 % p; a %= p;if(a < 0) a += p;while(b){ if(b & 1) (ans *= a) %= p; (a *= a) %= p; b /= 2; } return ans; }
bool is_clamp(ll val,ll low,ll high) {return low <= val && val < high;}
void Yes() {cout << "Yes\n";return;}
void No() {cout << "No\n";return;}
void YES() {cout << "YES\n";return;}
void NO() {cout << "NO\n";return;}
template <typename U,typename T>
U floor(U a, T b) {return a / b - (a % b && (a ^ b) < 0);}
// ceil(x,y) = floor(x+y-1,y)なのでx+y-1がoverflowする可能性あり
template <typename U,typename T>
U ceil(U x, T y) {return floor(x + y - 1, y);}
template <typename U,typename T>
T bmod(U x, T y) {return x - y * floor(x, y);}
template <typename U,typename T>
pair<U, T> divmod(U x, T y) {U q = floor(x, y);return {q, x - q * y};}
namespace IO{
#define VOID(a) decltype(void(a))
struct setting{ setting(){cin.tie(nullptr); ios::sync_with_stdio(false);fixed(cout); cout.precision(15);}} setting;
template<int I> struct P : P<I-1>{};
template<> struct P<0>{};
template<class T> void i(T& t){ i(t, P<3>{}); }
void i(vector<bool>::reference t, P<3>){ int a; i(a); t = a; }
template<class T> auto i(T& t, P<2>) -> VOID(cin >> t){ cin >> t; }
template<class T> auto i(T& t, P<1>) -> VOID(begin(t)){ for(auto&& x : t) i(x); }
template<class T, size_t... idx> void ituple(T& t, index_sequence<idx...>){in(get<idx>(t)...);}
template<class T> auto i(T& t, P<0>) -> VOID(tuple_size<T>{}){ituple(t, make_index_sequence<tuple_size<T>::value>{});} 
#undef VOID
}
#define unpack(a) (void)initializer_list<int>{(a, 0)...}
template<class... Ts> void in(Ts&... t){ unpack(IO :: i(t)); }
#undef unpack
constexpr long double PI = 3.141592653589793238462643383279L;
template <class F> struct REC {
    F f;
    REC(F &&f_) : f(forward<F>(f_)) {}
    template <class... Args> auto operator()(Args &&...args) const { return f(*this, forward<Args>(args)...); }};

constexpr int mod = 998244353;
//constexpr int mod = 1000000007;

void solve() {
    INT(n,q);
    vi L(n),R(n),C(n);
    rep(i,n) {
        cin >> L[i] >> R[i] >> C[i];
        L[i]--;
    }
    vi A(q),B(q);
    vl ans(q);
    vvi evt1(n),evt2(n+1);
    vi mid;
    vi LQ(q),RQ(q);
    rep(i,q) {
        cin >> A[i] >> B[i];
        A[i]--,B[i]--;
        if(R[A[i]] <= L[B[i]]);
        else if(R[B[i]] <= L[A[i]]) swap(A[i],B[i]);
        else {
            ans[i] = -1;
            continue;
        }
        ans[i] = C[A[i]] + C[B[i]];
        evt1[L[A[i]]].emplace_back(i);
        evt2[R[B[i]]].emplace_back(i);
        if(R[A[i]] < L[B[i]]) {
            mid.emplace_back(i);
            LQ[i] = R[A[i]];
            RQ[i] = L[B[i]];
        }
    }
    vi ord(n);
    iota(all(ord),0);
    vl REM(n);
    {
        sort(all(ord),[&](int i,int j){return R[i] < R[j];});
        int id = 0;
        vl dp(n + 1);
        rep(i,1,n+1) {
            dp[i] = dp[i-1];
            while(id < n && R[ord[id]] == i) {
                chmax(dp[i],dp[L[ord[id]]] + C[ord[id]]);
                id++;
            }
            for(auto &qid:evt1[i]) {
                ans[qid] += dp[i];
            }
        }
    }
    {
        sort(all(ord),[&](int i,int j){return L[i] > L[j];});
        int id = 0;
        vl dp(n + 1);
        rrep(i,n) {
            dp[i] = dp[i+1];
            while(id < n && L[ord[id]] == i) {
                chmax(dp[i],dp[R[ord[id]]] + C[ord[id]]);
                id++;
            }
            for(auto &qid:evt2[i]) {
                ans[qid] += dp[i];
            }
        }   
    }
    {
        auto dfs = REC([&](auto &f,int L1,int R1,vi &task,vi &query) -> void {
            if(task.empty() || query.empty()) return;
            if(R1 - L1 == 1) {
                int tmp = 0;
                rep(j,task.size()) chmax(tmp,C[task[j]]);
                rep(j,query.size()) REM[query[j]] += tmp;
                return;
            }
            int M1 = (L1 + R1) / 2;
            vi left,right,both;
            rep(i,task.size()) {
                if(R[task[i]] <= M1) left.emplace_back(task[i]);
                else if(L[task[i]] >= M1) right.emplace_back(task[i]);
                else both.emplace_back(task[i]);
            }
            vi lquery,rquery,bquery;
            rep(i,query.size()) {
                if(RQ[query[i]] <= M1) lquery.emplace_back(query[i]);
                else if(LQ[query[i]] >= M1) rquery.emplace_back(query[i]);
                else bquery.emplace_back(query[i]);
            }
            sort(all(left),[&](int i,int j){return L[i] > L[j];});
            sort(all(right),[&](int i,int j){return R[i] < R[j];});
            if(!bquery.empty()) {
                rep(time,both.size() + 1) {
                    ll add = time == both.size() ? 0 : C[both[time]];
                    int ML2 = time == both.size() ? M1 : L[both[time]];
                    int MR2 = time == both.size() ? M1 : R[both[time]];
                    vl dp1(ML2 - L1 + 1),dp2(R1 - MR2 + 1);
                    {
                        int id = 0;
                        rrep(i,L1,ML2) {
                            dp1[i-L1] = dp1[i-L1+1];
                            while(id < left.size() && L[left[id]] >= i) {
                                if(R[left[id]] <= ML2) chmax(dp1[i-L1],dp1[R[left[id]]-L1] + C[left[id]]);
                                id++;
                            }
                        }
                    }
                    {
                        int id = 0;
                        rep(i,MR2+1,R1+1) {
                            dp2[i-M1] = dp2[i-M1-1];
                            while(id < right.size() && R[right[id]] <= i) {
                                if(L[right[id]] >= MR2) chmax(dp2[i-M1],dp2[L[right[id]]-M1] + C[right[id]]);
                                id++;
                            }
                        }
                    }
                    rep(i,bquery.size()) {
                        if(LQ[bquery[i]] <= ML2 && RQ[bquery[i]] >= MR2) {
                            chmax(REM[bquery[i]],add + dp1[LQ[bquery[i]] - L1] + dp2[RQ[bquery[i]] - MR2]);
                        }
                    }
                }
            }
            f(L1,M1,left,lquery);
            f(M1,R1,right,rquery);
        });
        vi task(n);
        iota(all(task),0);
        dfs(0,n,task,mid);
        rep(i,q) {
            cout << ans[i] + REM[i] << '\n';
        }
    }
}

int main() {
    int TT = 1;
    //cin >> TT;
    while(TT--) solve();
}