#include <bits/stdc++.h>
using namespace std;
#define int long long
int n, d, q, a[300005], b[300005], c[300005], pre[300005];
int32_t main() {
ios::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
cin >> n >> d;
for (int i = 1 ; i <= n; i++) {
cin >> a[i]; c[i] = a[i];
b[i] = a[i] / d;
a[i] %= d;
if (a[i] < a[i - 1]) {
int tmp = (a[i - 1] - a[i] + d - 1) / d;
b[i] -= tmp;
a[i] += tmp * d;
}
pre[i] = pre[i - 1] + b[i];
}
cin >> q;
while (q--) {
int l, r; cin >> l >> r;
int ex = a[l] / d;
if (b[r] < -ex) { cout << -1 << '\n'; continue; }
int tmp = a[r] - ex * d;
ex -= (c[r] - tmp) / d;
cout << pre[r - 1] - pre[l - 1] + ex * (r - l) << '\n';
}
}
