#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define MOD 1000000007
void solve()
{
ll n, d, q, l, r;
cin >> n >> d;
vector<ll> c(n + 1), req(n + 1), mn(n + 1), pre1(n + 1), pre2(n + 1);
for (int i = 1; i <= n; i++)
{
cin >> c[i];
}
for (int i = n - 1; i > 0; i--)
{
req[i] = max(0ll, (c[i] - c[i + 1] + d - 1) / d + req[i + 1]);
}
priority_queue<pair<int, int>> pq;
req[0] = -1;
for (int i = n; i >= 0; i--)
{
pq.push({req[i], i});
while (req[i] < pq.top().first)
{
mn[pq.top().second] = i;
pq.pop();
}
}
for (int i = 1; i <= n; i++)
{
pre1[i] = pre1[mn[i]] + req[i] * (i - mn[i]);
pre2[i] = pre2[i - 1] + req[i];
}
vector<vector<ll>> bl(n + 1, vector<ll>(20, -1));
for (int i = 0; i <= n; i++)
{
bl[i][0] = mn[i];
}
for (int j = 1; j < 20; j++)
{
for (int i = 0; i <= n; i++)
{
bl[i][j] = bl[bl[i][j - 1]][j - 1];
}
}
cin >> q;
for (int i = 0; i < q; i++)
{
cin >> l >> r;
ll m = r;
for (int i = 19; i >= 0; i--)
{
if (bl[m][i] >= l)
{
m = bl[m][i];
}
}
if (c[l] < (req[l] - req[m]) * d)
{
cout << -1 << '\n';
}
else
{
cout << pre2[r] - pre2[l - 1] - (pre1[r] - pre1[m] + req[m] * (m - l + 1)) << '\n';
}
}
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int tests = 1;
// cin >> tests;
for (int i = 1; i <= tests; i++)
solve();
}
