#include <iostream>
#include <set>
#include <vector>
#include <algorithm>
#include <ctime>
#include <random>

#define f first
#define s second
#define pb push_back
using namespace std;

template<typename T1, typename T2> inline void chkmin(T1 & x, T2 y) {if (x > y) x = y;}
template<typename T1, typename T2> inline void chkmax(T1 & x, T2 y) {if (x < y) x = y;}

typedef long long ll;

const int MAXN = 3e5 + 1, BLOCK = 550, INF = 1e9;
int a[MAXN], cnt[MAXN], ans1[MAXN];
set<pair<int, int>> s;

bool cmp(pair<pair<int, int>, pair<int, int>> & a, pair<pair<int, int>, pair<int, int>> & b) {
    int bla = a.f.f / BLOCK, blb = b.f.f / BLOCK;
    if (bla != blb) return bla < blb;
    return a.f.s < b.f.s;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(0), cout.tie(0);
    // freopen("input.txt", "r", stdin);
    mt19937 shit(time(0));
    int n, q;
    cin >> n >> q;
    for (int i = 0; i < n; ++i) {
        cin >> a[i];
    }
    vector<pair<pair<int, int>, pair<int, int>>> reqs;
    reqs.reserve(q);
    for (int i = 0; i < q; ++i) {
        int l, r, k;
        cin >> l >> r >> k, --l, --r;
        reqs.pb({{l, r}, {k, i}});
    }
    // cout << "done\n";
    sort(reqs.begin(), reqs.end(), cmp);
    int l = 0, r = -1;
    for (auto i : reqs) {
        while (r < i.f.s)
            ++cnt[a[++r]];
        while (r > i.f.s)
            --cnt[a[r--]];
        while (l < i.f.f)
            --cnt[a[l++]];
        while (l > i.f.f)
            ++cnt[a[--l]];

        int ans = INF;
        int mn_met = (i.f.s - i.f.f + 1) / i.s.f + 1;
        // cout << i.s.s << ' ' << mn_met << endl;
        int len = i.f.s - i.f.f + 1;
        for (int j = 0; j < 100; ++j) {
            int kek = a[i.f.f + shit() % len];
            if (cnt[kek] >= mn_met)
                chkmin(ans, kek);
        }
        if (ans == INF)
            ans = -1;
        ans1[i.s.s] = ans;
    }
    // cout << endl << endl;
    for (int i = 0; i < q; ++i)
        cout << ans1[i] << '\n';
    return 0;
}