#include "bits/stdc++.h"
using namespace std;
#define forR(i, x) for(int i = 0; i < (x); ++i)
#define REP(i, a, b) for(int i = (a); i < (b); ++i)
typedef long long ll;
struct pii{int a, b;};
const int MN = 3e5 + 10, MQ = 3e5 + 10;
struct query{int l, r, i;};
ll c[MN];
ll ans[MQ];
vector<query> byR[MN];
ll ti[MN];
bool pos[MN];
ll ceilDiv(ll a, ll b){
return (a-1)/b+1;
}
int main() {
int n;
ll d; cin >> n >> d;
REP(i, 1, n+1) {
pos[i] = true;
}
REP(i, 1, n+1) cin >> c[i];
int q; cin >> q;
forR(i, q){
query cur={}; cin >> cur.l >> cur.r;
cur.i = i;
byR[cur.r].push_back(cur);
}
REP(i, 1, n+1){
for(int j = i-1; j > 0; --j) {
if(!pos[j+1]) pos[j] = false;
else if(c[j]-d*ti[j] > c[j+1]-d*ti[j+1]){
ll needed = ceilDiv(c[j]-d*ti[j]-(c[j+1]-d*ti[j+1]), d);
ti[j] += needed;
if(c[j]-ti[j] * d < 0) pos[j] = false;
}
}
for(auto [l, r, ind] : byR[i]){
for(int j = l; j <= i; ++j) if(!pos[j]) ans[ind] = -1;
if(ans[ind] != -1){
for(int j = l; j <= i; ++j){
ans[ind] += ti[j];
}
}
}
}
forR(i, q) cout << ans[i] << '\n';
}
