#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
#define pb push_back
#define ff first
#define ss second
struct DS{
vector<ll> a;
int n;
DS(int ns){
n = ns;
a.resize(n + 1);
}
void upd(int p, ll x){
a[p] = x;
for (int i = 1; i < p; i++){
a[i] = min(a[i], x);
}
}
ll get(int l, int r){
ll out = 0;
for (int i = l; i <= r; i++){
out += a[i];
}
return out;
}
};
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n; ll d; cin>>n>>d;
vector<ll> a(n + 1);
for (int i = 1; i <= n; i++){
cin>>a[i];
}
vector<ll> x(n);
for (int i = 1; i < n; i++){
x[i] = -ceil(1.0 * (a[i] - a[i + 1]) / d);
}
vector<ll> y(n + 1);
for (int i = 2; i <= n; i++){
y[i] = y[i - 1] + x[i - 1];
}
vector<ll> p(n + 1);
for (int i = 1; i <= n; i++){
p[i] = p[i - 1] + y[i];
}
int q; cin>>q;
vector<pii> end[n + 1];
for (int i = 1; i <= q; i++){
int l, r; cin>>l>>r;
end[r].pb({l, i});
}
vector<ll> out(q + 1);
DS T(n);
for (int r = 1; r <= n; r++){
T.upd(r, y[r]);
for (auto [l, ii]: end[r]){
ll h = T.get(l, l) - y[l];
if ((a[l] + h * d) < 0){
out[ii] = -1;
continue;
}
out[ii] = (p[r] - p[l - 1]) - T.get(l, r);
}
}
for (int i = 1; i <= q; i++){
cout<<out[i]<<"\n";
}
}
