#include <bits/stdc++.h>
using namespace std;
mt19937_64 rng(time(0));
using ll = long long;
#define int long long
const int N = 2e5 + 1;
void solve() {
int n, d; cin >> n >> d;
vector<int> c(n + 1), pref (n + 1), a(n + 1), b(n + 1);
vector<int>p2(n + 1);
vector<int>p3(n + 1);
vector<int>p4(n + 1);
for (int i = 1; i <= n; ++i) {
cin >> c[i];
a[i] = c[i] / d;
b[i] = c[i] % d;
pref[i] = pref[i - 1] + c[i];
p2[i] = p2[i - 1] + a[i];
}
for (int i = 1; i < n; ++i) {
p3[i] = p3[i - 1] + bool (b[i] > b[i + 1]);
p4[i] = p4[i - 1] + (b[i] > b[i + 1] ? i : 0);
}
int q; cin >> q;
vector<int> id(n + 1);
for (int i = 1; i <= n; ++i) {
int nw = a[i];
for (int j = i - 1; j >= 1; j -= 1) {
if (a[j] >= nw) {
if (b[j] > b[j + 1]) nw -= 1;
} else {
id[i] = j;
break;
}
}
}
while (q--) {
int l, r; cin >> l >> r;
int wr = r;
int ans = 0;
bool bad = 0;
int mnO = a[r];
// r -= 1;
// while (r >= l) {
// if (a[r] >= mnO) {
// if (b[r] > b[r + 1]) {
// mnO -= 1;
// }
// ans += a[r] - mnO;
// }
// else {
// mnO = a[r];
// }
// --r;
// if (mnO < 0) bad = 1;
// }
//
// cout << (!bad ? ans : -1) << '\n';
r = wr;
ans = 0;
bad = 0;
mnO = a[r];
while (r >= l) {
int ps = max (l, id[r] + 1);
ans += p2[r - 1] - p2[ps - 1];
mnO = a[r];
ans -= mnO * (r - ps);
int all = p4[r - 1] - p4[ps - 1];
int cnt = p3[r - 1] - p3[ps - 1];
ans += all - (ps - 1) * cnt;
r = id[r];
if (mnO < 0) {
bad = 1;
break;
}
}
cout << (!bad ? ans : -1) << '\n';
}
}
int32_t main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif // LOCAL
int T = 1;
while (T--) solve();
return 0;
}
