#include <bits/stdc++.h>
using namespace std;
string abc = "abcdefghijklmnopqrstuvwxyz";
#define int long long
const int N = 2e5+7;
int a[N], t[4*N];
void merge(int v){
if(min(t[2*v], t[2*v+1]) == -2e18-7){
t[v]=-2e18-7;
return;
}
t[v]=t[2*v]+t[2*v+1];
}
void in(int v, int tl, int tr){
if(tl == tr){
t[v]=a[tl];
return;
}
int tm=(tl+tr)/2;
in(2*v, tl, tm);
in(2*v+1, tm+1, tr);
merge(v);
}
int get(int v, int tl, int tr, int l, int r){
if(tl == l && tr == r){
return t[v];
}
int tm = (tl+tr)/2;
if(tm >= r) return get(2*v, tl, tm, l, r);
if(tm < l) return get(2*v+1, tm+1, tr, l, r);
return get(2*v, tl, tm, l, tm)+get(2*v+1, tm+1, tr, tm+1, r);
}
void solve(){
int n, k;
cin >> n >> k;
vector<int> v(n+1);
for(int i = 1; i <= n; i++) cin >> v[i];
a[n]=0;
for(int i = 1; i < n; i++){
if(v[i] <= v[i+1]){
a[i]=0;
}
else{
int dif = v[i]-v[i+1];
int aux = k-dif%k;
if(aux == k) aux = 0;
int ans = aux;
// if(k-aux == k) ans = 0;
if(ans > v[i+1]){
a[i]=-2e18-7;
continue;
}
ans+=(v[i]-(v[i+1]-aux))/k;
a[i]=ans;
}
// cout << a[i] << " ";
}
// cout << "t" << endl;
in(1, 1, n);
int q;
cin >> q;
while(q--){
int l, r;
cin >> l >> r;
if(r <= l){
cout << 0 << endl;
}
else{
int ans = get(1, 1, n, l, r-1);
if(ans >= 0) cout << ans << endl;
else cout << -1 << endl;
}
}
}
signed main(){
int t = 1;
while(t--){
solve();
}
}
