#line 1 "main.cpp"
#line 1 "main.cpp"
#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 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; 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);}
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;
#line 2 "library/segtree/lazysegtree.hpp"
template <class S,
          S (*op)(S, S),
          S (*e)(),
          class F,
          S (*mapping)(F, S),
          F (*composition)(F, F),
          F (*id)()>
struct lazy_segtree {
  public:
    lazy_segtree() : lazy_segtree(0) {}
    explicit lazy_segtree(int n) : lazy_segtree(vector<S>(n, e())) {}
    explicit lazy_segtree(const vector<S>& v) : _n(int(v.size())) {
        log = 0;
        while ((1U << log) < (unsigned int)(_n)) log++;
        size = 1 << log;
        d = vector<S>(2 * size, e());
        lz = vector<F>(size, id());
        for (int i = 0; i < _n; i++) d[size + i] = v[i];
        for (int i = size - 1; i >= 1; i--) {
            update(i);
        }
    }

    void set(int p, S x) {
        assert(0 <= p && p < _n);
        p += size;
        for (int i = log; i >= 1; i--) push(p >> i);
        d[p] = x;
        for (int i = 1; i <= log; i++) update(p >> i);
    }

    S get(int p) {
        assert(0 <= p && p < _n);
        p += size;
        for (int i = log; i >= 1; i--) push(p >> i);
        return d[p];
    }

    S prod(int l, int r) {
        assert(0 <= l && l <= r && r <= _n);
        if (l == r) return e();

        l += size;
        r += size;

        for (int i = log; i >= 1; i--) {
            if (((l >> i) << i) != l) push(l >> i);
            if (((r >> i) << i) != r) push((r - 1) >> i);
        }

        S sml = e(), smr = e();
        while (l < r) {
            if (l & 1) sml = op(sml, d[l++]);
            if (r & 1) smr = op(d[--r], smr);
            l >>= 1;
            r >>= 1;
        }

        return op(sml, smr);
    }

    S all_prod() { return d[1]; }

    void apply(int p, F f) {
        assert(0 <= p && p < _n);
        p += size;
        for (int i = log; i >= 1; i--) push(p >> i);
        d[p] = mapping(f, d[p]);
        for (int i = 1; i <= log; i++) update(p >> i);
    }
    void apply(int l, int r, F f) {
        assert(0 <= l && l <= r && r <= _n);
        if (l == r) return;

        l += size;
        r += size;

        for (int i = log; i >= 1; i--) {
            if (((l >> i) << i) != l) push(l >> i);
            if (((r >> i) << i) != r) push((r - 1) >> i);
        }

        {
            int l2 = l, r2 = r;
            while (l < r) {
                if (l & 1) all_apply(l++, f);
                if (r & 1) all_apply(--r, f);
                l >>= 1;
                r >>= 1;
            }
            l = l2;
            r = r2;
        }

        for (int i = 1; i <= log; i++) {
            if (((l >> i) << i) != l) update(l >> i);
            if (((r >> i) << i) != r) update((r - 1) >> i);
        }
    }

    template <bool (*g)(S)> int max_right(int l) {
        return max_right(l, [](S x) { return g(x); });
    }
    template <class G> int max_right(int l, G g) {
        assert(0 <= l && l <= _n);
        assert(g(e()));
        if (l == _n) return _n;
        l += size;
        for (int i = log; i >= 1; i--) push(l >> i);
        S sm = e();
        do {
            while (l % 2 == 0) l >>= 1;
            if (!g(op(sm, d[l]))) {
                while (l < size) {
                    push(l);
                    l = (2 * l);
                    if (g(op(sm, d[l]))) {
                        sm = op(sm, d[l]);
                        l++;
                    }
                }
                return l - size;
            }
            sm = op(sm, d[l]);
            l++;
        } while ((l & -l) != l);
        return _n;
    }

    template <bool (*g)(S)> int min_left(int r) {
        return min_left(r, [](S x) { return g(x); });
    }
    template <class G> int min_left(int r, G g) {
        assert(0 <= r && r <= _n);
        assert(g(e()));
        if (r == 0) return 0;
        r += size;
        for (int i = log; i >= 1; i--) push((r - 1) >> i);
        S sm = e();
        do {
            r--;
            while (r > 1 && (r % 2)) r >>= 1;
            if (!g(op(d[r], sm))) {
                while (r < size) {
                    push(r);
                    r = (2 * r + 1);
                    if (g(op(d[r], sm))) {
                        sm = op(d[r], sm);
                        r--;
                    }
                }
                return r + 1 - size;
            }
            sm = op(d[r], sm);
        } while ((r & -r) != r);
        return 0;
    }

  private:
    int _n, size, log;
    vector<S> d;
    vector<F> lz;

    void update(int k) { d[k] = op(d[2 * k], d[2 * k + 1]); }
    void all_apply(int k, F f) {
        d[k] = mapping(f, d[k]);
        if (k < size) lz[k] = composition(f, lz[k]);
    }
    void push(int k) {
        all_apply(2 * k, lz[k]);
        all_apply(2 * k + 1, lz[k]);
        lz[k] = id();
    }
};
#line 100 "main.cpp"

const ll LINF = 0x1fffffffffffffff;
ll op(ll x,ll y) {return max(x,y);}
ll e() {return -LINF;}
ll mapping(ll f,ll x) { 
    return max(f,x);
}
ll composition (ll L,ll R) {
    return max(L,R);
}
ll id() {return -LINF;}
#line 2 "segment-tree/segment-tree-beats.hpp"

struct AngelBeats {
  using i64 = long long;
  static constexpr i64 INF = numeric_limits<i64>::max() / 2.1;

  struct alignas(32) Node {
    i64 sum = 0, g1 = 0, l1 = 0;
    i64 g2 = -INF, gc = 1, l2 = INF, lc = 1, add = 0;
  };

  vector<Node> v;
  i64 n, log;

  AngelBeats() {}
  AngelBeats(int _n) : AngelBeats(vector<i64>(_n)) {}
  AngelBeats(const vector<i64>& vc) {
    n = 1, log = 0;
    while (n < (int)vc.size()) n <<= 1, log++;
    v.resize(2 * n);
    for (i64 i = 0; i < (int)vc.size(); ++i) {
      v[i + n].sum = v[i + n].g1 = v[i + n].l1 = vc[i];
    }
    for (i64 i = n - 1; i; --i) update(i);
  }

  void range_chmin(int l, int r, i64 x) { inner_apply<1>(l, r, x); }
  void range_chmax(int l, int r, i64 x) { inner_apply<2>(l, r, x); }
  void range_add(int l, int r, i64 x) { inner_apply<3>(l, r, x); }
  void range_update(int l, int r, i64 x) { inner_apply<4>(l, r, x); }
  i64 range_min(int l, int r) { return inner_fold<1>(l, r); }
  i64 range_max(int l, int r) { return inner_fold<2>(l, r); }
  i64 range_sum(int l, int r) { return inner_fold<3>(l, r); }

 private:
  void update(int k) {
    Node& p = v[k];
    Node& l = v[k * 2 + 0];
    Node& r = v[k * 2 + 1];

    p.sum = l.sum + r.sum;

    if (l.g1 == r.g1) {
      p.g1 = l.g1;
      p.g2 = max(l.g2, r.g2);
      p.gc = l.gc + r.gc;
    } else {
      bool f = l.g1 > r.g1;
      p.g1 = f ? l.g1 : r.g1;
      p.gc = f ? l.gc : r.gc;
      p.g2 = max(f ? r.g1 : l.g1, f ? l.g2 : r.g2);
    }

    if (l.l1 == r.l1) {
      p.l1 = l.l1;
      p.l2 = min(l.l2, r.l2);
      p.lc = l.lc + r.lc;
    } else {
      bool f = l.l1 < r.l1;
      p.l1 = f ? l.l1 : r.l1;
      p.lc = f ? l.lc : r.lc;
      p.l2 = min(f ? r.l1 : l.l1, f ? l.l2 : r.l2);
    }
  }

  void push_add(int k, i64 x) {
    Node& p = v[k];
    p.sum += x << (log + __builtin_clz(k) - 31);
    p.g1 += x;
    p.l1 += x;
    if (p.g2 != -INF) p.g2 += x;
    if (p.l2 != INF) p.l2 += x;
    p.add += x;
  }
  void push_min(int k, i64 x) {
    Node& p = v[k];
    p.sum += (x - p.g1) * p.gc;
    if (p.l1 == p.g1) p.l1 = x;
    if (p.l2 == p.g1) p.l2 = x;
    p.g1 = x;
  }
  void push_max(int k, i64 x) {
    Node& p = v[k];
    p.sum += (x - p.l1) * p.lc;
    if (p.g1 == p.l1) p.g1 = x;
    if (p.g2 == p.l1) p.g2 = x;
    p.l1 = x;
  }
  void push(int k) {
    Node& p = v[k];
    if (p.add != 0) {
      push_add(k * 2 + 0, p.add);
      push_add(k * 2 + 1, p.add);
      p.add = 0;
    }
    if (p.g1 < v[k * 2 + 0].g1) push_min(k * 2 + 0, p.g1);
    if (p.l1 > v[k * 2 + 0].l1) push_max(k * 2 + 0, p.l1);

    if (p.g1 < v[k * 2 + 1].g1) push_min(k * 2 + 1, p.g1);
    if (p.l1 > v[k * 2 + 1].l1) push_max(k * 2 + 1, p.l1);
  }

  void subtree_chmin(int k, i64 x) {
    if (v[k].g1 <= x) return;
    if (v[k].g2 < x) {
      push_min(k, x);
      return;
    }
    push(k);
    subtree_chmin(k * 2 + 0, x);
    subtree_chmin(k * 2 + 1, x);
    update(k);
  }

  void subtree_chmax(int k, i64 x) {
    if (x <= v[k].l1) return;
    if (x < v[k].l2) {
      push_max(k, x);
      return;
    }
    push(k);
    subtree_chmax(k * 2 + 0, x);
    subtree_chmax(k * 2 + 1, x);
    update(k);
  }

  template <int cmd>
  inline void _apply(int k, i64 x) {
    if constexpr (cmd == 1) subtree_chmin(k, x);
    if constexpr (cmd == 2) subtree_chmax(k, x);
    if constexpr (cmd == 3) push_add(k, x);
    if constexpr (cmd == 4) subtree_chmin(k, x), subtree_chmax(k, x);
  }

  template <int cmd>
  void inner_apply(int l, int r, i64 x) {
    if (l == r) return;
    l += n, r += n;
    for (int i = log; i >= 1; i--) {
      if (((l >> i) << i) != l) push(l >> i);
      if (((r >> i) << i) != r) push((r - 1) >> i);
    }
    {
      int l2 = l, r2 = r;
      while (l < r) {
        if (l & 1) _apply<cmd>(l++, x);
        if (r & 1) _apply<cmd>(--r, x);
        l >>= 1;
        r >>= 1;
      }
      l = l2;
      r = r2;
    }
    for (int i = 1; i <= log; i++) {
      if (((l >> i) << i) != l) update(l >> i);
      if (((r >> i) << i) != r) update((r - 1) >> i);
    }
  }

  template <int cmd>
  inline i64 e() {
    if constexpr (cmd == 1) return INF;
    if constexpr (cmd == 2) return -INF;
    return 0;
  }

  template <int cmd>
  inline void op(i64& a, const Node& b) {
    if constexpr (cmd == 1) a = min(a, b.l1);
    if constexpr (cmd == 2) a = max(a, b.g1);
    if constexpr (cmd == 3) a += b.sum;
  }

  template <int cmd>
  i64 inner_fold(int l, int r) {
    if (l == r) return e<cmd>();
    l += n, r += n;
    for (int i = log; i >= 1; i--) {
      if (((l >> i) << i) != l) push(l >> i);
      if (((r >> i) << i) != r) push((r - 1) >> i);
    }
    i64 lx = e<cmd>(), rx = e<cmd>();
    while (l < r) {
      if (l & 1) op<cmd>(lx, v[l++]);
      if (r & 1) op<cmd>(rx, v[--r]);
      l >>= 1;
      r >>= 1;
    }
    if constexpr (cmd == 1) lx = min(lx, rx);
    if constexpr (cmd == 2) lx = max(lx, rx);
    if constexpr (cmd == 3) lx += rx;
    return lx;
  }
};

/**
 * @brief Range Chmin Chmax Add Update Range Min Max Sum Segment Tree Beats!
 * @docs docs/segment-tree/segment-tree-beats.md
 */
void solve() {
    INT(n,k,q);
    VEC(ll,a,n);
    vector<tuple<int,int,int>> update(k);
    rep(i,k) {
        INT(l,r,x);
        l--;
        update[i] = {l,r,x};
    }
    vector<tuple<int,int,ll>> query(q);
    rep(i,q) {
        INT(l,r);
        LL(x);
        l--;
        query[i] = {l,r,x};
    }
    vl cs(n+1);
    rep(i,n) {
        cs[i+1] = cs[i] + a[i];
    }
    vi ans(q,1e9);
    rep(i,q) {
        auto [l,r,x] = query[i];
        if(cs[r] - cs[l] >= x) ans[i] = 0;
    }
    lazy_segtree<ll,op,e,ll,mapping,composition,id> seg1(a);
    rep(i,k) {
        auto [l,r,x] = update[i];
        seg1.apply(l,r,x);
    }
    vl lascs(n+1);
    rep(i,n) {
        lascs[i+1] = lascs[i] + seg1.get(i);
    }
    rep(i,q) {
        auto [l,r,x] = query[i];
        if(lascs[r] - lascs[l] < x) ans[i] = -1;
    }
    vi V;
    rep(i,q) {
        if(ans[i] == (int)1e9) V.emplace_back(i);
    }
    vector<pair<vi,pii>> dat;
    dat.emplace_back(V,pii{0,k});
    while(!dat.empty()) {
        debug(dat);
        vector<pair<vi,pii>> ndat;
        AngelBeats AB(a);
        int OP = 0;
        for(auto &[VV,pa]:dat) {
            auto [ng,ok] = pa;
            if(ok - ng == 1) {
                for(auto &id:VV) {
                    ans[id] = ok;
                }
            }
            else {
                int mid = (ng + ok) / 2;
                rep(j,OP,mid) {
                    auto [l,r,x] = update[j];
                    AB.range_chmax(l,r,x);
                }
                OP = mid;
                vi V1,V2;
                for(auto &id:VV) {
                    auto [l,r,x] = query[id];
                    if(AB.range_sum(l,r) >= x) V1.emplace_back(id);
                    else V2.emplace_back(id);
                }
                debug(ok,mid,ng);
                assert(ok != mid && ng != mid);
                if(!V1.empty()) ndat.emplace_back(V1,pii{ng,mid});
                if(!V2.empty()) ndat.emplace_back(V2,pii{mid,ok});
            }
        }
        dat = move(ndat);
    }
    rep(i,q) cout << ans[i] << '\n';
}    



int main() {
    //INT(TT);
    int TT = 1;
    rep(i,TT) solve();
}