#include <bits/stdc++.h>
#define int long long
#define ll long long
#define pb push_back
#define fi first
#define se second
#define lf (id<<1)
#define rg ((id<<1)|1)
#define md ((l+r)>>1)
#define ld long double
using namespace std;
typedef pair<int,int> pii;
typedef pair<char,char> pcc;
typedef pair<int,pii> ipii;
typedef pair<pii,pii> ipiii;
const int MAXN = 3e5+50;
const int SQRT = 610;
const int MAXA = 50;
const int MOD = 998244353;
const int LOG = 21;
const int INF = 1e16+100;
const int INF2 = 1e18;
const ld EPS = 1e-12;
int n, d, c[MAXN], ans[MAXN], val[MAXN], su[MAXN];
vector <pii> que[MAXN];
struct seg {
int st[4*MAXN], laz[4*MAXN];
void bd(int id, int l, int r){
laz[id] = -1;
if(l==r) return;
bd(lf,l,md); bd(rg,md+1,r);
}
void bnc(int id, int l, int r){
if(laz[id]==-1) return;
laz[lf] = laz[id]; st[lf] = (md-l+1) * laz[id];
laz[rg] = laz[id]; st[rg] = (r-md) * laz[id];
laz[id] = -1;
}
int que(int id, int l, int r, int x, int y){
if(x<=l && r<=y) return st[id];
if(r<x || y<l) return 0;
bnc(id,l,r);
return que(lf,l,md,x,y) + que(rg,md+1,r,x,y);
}
int upd(int id, int l, int r, int x, int y, int p){
if(x<=l && r<=y){
laz[id] = p;
return st[id] = (r-l+1) * p;
}
if(r<x || y<l) return st[id];
bnc(id,l,r);
return st[id] = upd(lf,l,md,x,y,p) + upd(rg,md+1,r,x,y,p);
}
} A;
signed main(){
// ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
cin>>n>>d;
for(int i=1; i<=n; i++){
cin >> c[i];
}
for(int i=n-1; i>=1; i--){
val[i] = val[i+1] + (c[i]-c[i+1]+d-1)/d;
su[i] = su[i+1] + val[i];
// cout << i << ' ' << val[i] << ' ' << su[i] << " pp\n";
}
int q; cin>>q;
for(int i=1; i<=q; i++){
int l, r; cin>>l>>r;
if(l==r){ ans[i] = 0; continue; }
r--;
if((val[l]-val[r+1])*d > c[l]){ ans[i] = -1; continue; }
ans[i] = su[l]-su[r+1] - (r-l+1) * val[r+1];
// cout << su[l]-su[r+1] << " su\n";
}
for(int i=1; i<=q;i++) cout << ans[i] << " \n";
}
