#include <bits/stdc++.h>
using namespace std;
const int logn = 20;
int main(){
ios_base::sync_with_stdio(false);
cin.tie(0);
int n;
long long d;
cin>>n>>d;
vector<long long> v(n);
for(auto &x : v) cin>>x;
vector<long long> diff(n);
for(int i = 0; i < n - 1; i++) {
if(v[i] <= v[i+1]) diff[i] = (v[i] - v[i + 1]) / d;
else diff[i] = (v[i] - v[i + 1] + d - 1) / d;
}
diff[n-1] = 0;
vector<long long> suf = diff;
for(int i = n-2; i >= 0; i--) {
suf[i] += suf[i + 1];
}
vector<long long> suf2 = suf;
for(int i = n-2; i >= 0; i--) {
suf2[i] += suf2[i + 1];
}
vector<array<pair<int, long long>, logn>> st(n);
for(int i = 0; i < n; i++) {
int idx = i - 1;
while(idx >= 0 && suf[idx] >= suf[i]) idx = st[idx][0].first;
st[i][0].first = idx;
}
// cout << "suf: ";
// for(auto x : suf) cout << x << ' ';
// cout << '\n';
// cout << "suf2: ";
// for(auto x : suf2) cout << x << ' ';
// cout << '\n';
for(int i = 0; i < n; i++) {
st[i][0].second = suf2[st[i][0].first + 1] - suf2[i] - (i - (st[i][0].first + 1)) * suf[i];
// cout << i << " | " << st[i][0].first << " | " << st[i][0].second << '\n';
}
for(int i = 0; i < n; i++) {
for(int j = 1; j < logn; j++) {
if(st[i][j-1].first != -1) {
st[i][j].first = st[st[i][j-1].first][j-1].first;
st[i][j].second = st[st[i][j-1].first][j-1].second + st[i][j-1].second;
} else {
st[i][j].first = -1;
st[i][j].second = 0;
}
}
}
int q;
cin>>q;
while(q--) {
int l, r;
cin>>l>>r;
--l, --r;
int x = r;
long long ans = 0;
for(int j = logn - 1; j >= 0; j--) {
if(st[x][j].first >= l) {
// cout << "jump: " << j << " | " << st[x][j].first << '\n';
ans += st[x][j].second;
x = st[x][j].first;
}
}
ans += (suf2[l] - suf2[x]) - (x - l) * suf[x];
if(v[l] - (suf[l] - suf[x]) * d < 0) {
cout << -1 << '\n';
} else {
cout << ans << '\n';
}
}
return 0;
}
