// ロンリーガールはいつまでも
// 届かない夢見て
#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "algo/debug.h"
#else
#define debug(...) 42
#endif
int main() {
int n;
cin >> n;
long long d;
cin >> d;
vector<long long> a(n);
for (int i = 0; i < n; i++) {
cin >> a[i];
}
vector<long long> x(n - 1);
for (int i = 0; i < n - 1; i++) {
if (a[i] - a[i + 1] <= 0) {
x[i] = -((a[i + 1] - a[i]) / d);
} else {
x[i] = (a[i] - a[i + 1] + d - 1) / d;
}
}
vector<long long> pref(n);
for (int i = 1; i < n; i++) {
pref[i] = pref[i - 1] + x[i - 1];
}
vector<vector<int>> prv(n, vector<int>(20, -1));
stack<pair<long long, int>> st;
vector<long long> prefpref(n);
vector<vector<long long>> vals(n, vector<long long>(20));
for (int i = 1; i < n; i++) {
prefpref[i] = prefpref[i - 1] + pref[i];
}
// in order to calculate for some range [l ... r]
// we need to find pref[r] - pref[l - 1] + pref[r] - pref[l] + ... +
// this is basically [prv[r][j] + 1 ... r]
// pref[r] - pref[prv[r][j]] + pref[r] - pref[prv[r][j] + 1] + ... + pref[r] - pref[r]
auto calc = [&](int l, int r) {
if (l > r) {
return 0ll;
}
long long rn = (static_cast<long long>(r - l + 1) * static_cast<long long>(pref[r]) - prefpref[r - 1]);
if (l != 1) {
rn += prefpref[l - 2];
}
return rn;
};
for (int i = 0; i < n; i++) {
while (!st.empty() && st.top().first <= pref[i]) {
st.pop();
}
if (!st.empty()) {
prv[i][0] = st.top().second;
}
if (prv[i][0] != -1) {
vals[i][0] = calc(prv[i][0] + 2, i);
}
st.push(make_pair(pref[i], i));
}
for (int j = 1; j < 20; j++) {
for (int i = 0; i < n; i++) {
if (prv[i][j - 1] == -1) {
prv[i][j] = -1;
} else {
prv[i][j] = prv[prv[i][j - 1]][j - 1];
vals[i][j] = vals[i][j - 1] + vals[prv[i][j - 1]][j - 1];
}
}
}
int q;
cin >> q;
for (int qq = 0; qq < q; qq++) {
int l, r;
cin >> l >> r;
// start from r - 1, and go till l
// till when do you have >= 0 prefix sum?
if (l == r) {
cout << 0 << '\n';
continue;
}
long long ans = 0;
int x = r - 1, xx = -1;
for (int j = 19; j >= 0; j--) {
if (prv[x][j] >= l - 1) {
ans += vals[x][j];
if (prv[x][j] == l - 1) {
xx = x;
}
x = prv[x][j];
}
}
// if at x, we're 0, what are we at l?
// pref[x - 1] - pref[l - 1]
ans += calc(l, x);
if (static_cast<long long>(pref[x] - pref[l - 1]) * d > a[l - 1]) {
cout << -1 << '\n';
} else {
if (xx != -1 && static_cast<long long>(pref[xx] - pref[l - 1]) * d > a[l - 1]) {
cout << -1 << '\n';
} else {
cout << ans << '\n';
}
}
}
return 0;
}
