#include <bits/stdc++.h> using namespace std; #define POPCOUNT(n) (__builtin_popcountll((n))) #define CLZ(n) (__builtin_clzll((n))) #define CTZ(n) (__builtin_ctzll((n))) #define LOG(n) (63 - __builtin_clzll((n))) #define BIT(n, i) (((n) >> (i)) & 1ll) #define MASK(i) (1ll << (i)) #define FLIP(n, i) ((n) ^ (1ll << (i))) #define ON(n, i) ((n) | MASK(i)) #define OFF(n, i) ((n) & ~MASK(i)) #define Int __int128 #define fi first #define se second typedef long long ll; typedef unsigned long long ull; typedef long double ld; typedef pair<int, int> pii; typedef pair<long long, long long> pll; typedef pair<long long, int> pli; typedef pair<int, long long> pil; typedef vector<pair<int, int>> vii; typedef vector<pair<long long, long long>> vll; typedef vector<pair<long long, int>> vli; typedef vector<pair<int, long long>> vil; template <class T1, class T2> bool maximize(T1 &x, T2 y) { if (x < y) { x = y; return true; } return false; } template <class T1, class T2> bool minimize(T1 &x, T2 y) { if (x > y) { x = y; return true; } return false; } template <class T> void remove_duplicate(vector<T> &ve) { sort (ve.begin(), ve.end()); ve.resize(unique(ve.begin(), ve.end()) - ve.begin()); } mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count()); long long random(long long l, long long r) { return uniform_int_distribution<long long>(l, r)(rng); } unsigned long long random(unsigned long long l, unsigned long long r) { return uniform_int_distribution<unsigned long long>(l, r)(rng); } template <class T> T random(T r) { return rng() % r; } const int N = 3e5 + 5, LG = 19; const int MOD = 1e9 + 7; const int inf = 1e9; const long long INF = 1e18; int n, q; ll D; int jump[N][LG]; ll c[N], f[N], suf[N], pref[N], pref_cost[N], cost[N][LG]; ll get_cost(int l, int r) { // c(i) - (suf[i] - suf[r + 1]) * D >= 0 // c(i) - suf[i] * D + suf[r + 1] * D >= 0 // c(i) - suf[i] * D >= -suf[r + 1] * D return (pref_cost[r] - pref_cost[l - 1]) - (pref[r] - pref[l - 1]) * (l - 1); } ll solve(int l, int r) { int p = r - 1; ll ans = 0; for (int i = LG - 1; i >= 0; --i) if (jump[p][i] >= l) { ans += cost[p][i]; p = jump[p][i]; } ans += get_cost(l, p); return ans; } signed main() { ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL); cin >> n >> D; for (int i = 1; i <= n; ++i) cin >> c[i]; for (int i = 1; i < n; ++i) { if (c[i] > c[i + 1]) f[i] = (c[i] - c[i + 1] + D - 1) / D; else f[i] = -((c[i + 1] - c[i]) / D); } suf[n] = 0; for (int i = n - 1; i > 0; --i) suf[i] = suf[i + 1] + f[i]; for (int i = 1; i < n; ++i) { pref[i] = pref[i - 1] + f[i]; pref_cost[i] = pref_cost[i - 1] + f[i] * i; } stack<int> st; st.emplace(1); for (int i = 1; i < n; ++i) { while (!st.empty() && suf[st.top()] > suf[i + 1]) st.pop(); if (st.empty()) jump[i][0] = -1; else jump[i][0] = st.top() - 1; st.emplace(i + 1); } // for (int i = 1; i < n; ++i) { // cerr << suf[i] << ' '; // } // cerr << '\n'; for (int i = 1; i < n; ++i) { cerr << jump[i][0] << ' '; } cerr << '\n'; for (int i = 1; i < n; ++i) { cost[i][0] = get_cost(jump[i][0] + 2, i); if (jump[i][0] == -1) jump[i][0] = 0; } for (int i = 1; i < LG; ++i) for (int j = 1; j < n; ++j) { jump[j][i] = jump[jump[j][i - 1]][i - 1]; cost[j][i] = cost[j][i - 1] + cost[jump[j][i - 1]][i - 1]; } cin >> q; while (q--) { int l, r; cin >> l >> r; ll k = 0, ans = 0; for (int i = r - 1; i >= l; --i) { // c(i) - k * D <= pre // k >= ceil((c(i) - pre) / D) if (c[i] > c[i + 1]) k += f[i]; else k = max(0ll, k + f[i]); if (c[i] - k * D < 0) { ans = -1; break; } ans += k; } cout << ans << '\n'; // if (ans == -1) cout << "-1\n"; // else cout << solve(l, r) << '\n'; } return 0; }