#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using ld = double;
int main() {
//~ ofstream cout("out.txt");
ios::sync_with_stdio(0);
cin.tie(0);
int n;
ll d;
cin >> n >> d;
vector<ll> a(n);
vector<ll> ps(n);
for (int i = 0; i < n; ++i) {
cin >> a[i];
ps[i] += a[i];
if (i) ps[i] += ps[i - 1];
}
vector<int> left(n, -1);
for (int i = 0; i < n; ++i) {
left[i] = (a[i] == 0 ? i : -1);
if (i) left[i] = max(left[i], left[i - 1]);
}
int q;
cin >> q;
while (q--) {
int l, r;
cin >> l >> r;
--l; --r;
ll take = a[r];
ll res = 0;
bool ok = true;
for (int i = r - 1; i >= l; --i) {
ll left = 0, right = (a[i]) / d;
ll now = -1;
//~ cerr << take << " -> ";
while (left <= right) {
ll mid = (left + right) / 2;
ll na = a[i] - mid * d;
if (na <= take) {
right = mid - 1;
now = mid;
} else {
left = mid + 1;
}
}
if (now == -1) {
ok = false;
break;
}
res += now;
take = a[i] - now * d;
}
//~ cerr << "res = ";
if (!ok) cout << "-1\n";
else cout << res << "\n";
}
}
