#include<iostream>
#include<stdio.h>
#include<math.h>
#include<map>
#include<string>
#include<algorithm>
#include<vector>
#include<string.h>
#include<utility>
#include<set>
#include<cmath>
#include<queue>
#include<deque>
#include<functional>
#include<stack>
#include<limits.h>
#include<iomanip>
#include<unordered_map>
using namespace std;
#define MOD 1000000007
#define int long long
#define endl '\n'
#define ff first
#define ss second
typedef pair<int,int> pp;
void solve(){
int n,d; cin>>n>>d;
vector<int> a(n+1);
for(int i=1; i<=n; i++) cin>>a[i];
vector<int> dp(n+1),pref(n+2),comp(n+1);
dp[n]=a[n];
for(int i=n-1; i>=1; i--){
if(a[i]>dp[i+1]){
comp[i]=((a[i]-dp[i+1])+(d-1))/d;
dp[i]=a[i]-((a[i]-dp[i+1])+(d-1))/d*d;
pref[i]=pref[i+1]+((a[i]-dp[i+1])+(d-1))/d;
}else{
comp[i]=0;
dp[i]=a[i];
pref[i]=pref[i+1];
}
}
stack<int> s;
s.push(0);
vector<vector<pp> > p(n+1,vector<pp>(20));
for(int i=1; i<=n; i++){
while(s.size()>1&&comp[s.top()]>=comp[i]) s.pop();
p[i][0]=make_pair(s.top(),comp[i]*(i-s.top()));
s.push(i);
}
for(int i=1; i<20; i++){
for(int j=1; j<=n; j++){
p[j][i].ff=p[p[j][i-1].ff][i-1].ff;
p[j][i].ss=p[j][i-1].ss+p[p[j][i-1].ff][i-1].ss;
}
}
int q; cin>>q;
while(q--){
int l,r; cin>>l>>r;
int cur=r,sum=0;
int ans=pref[l]-pref[r+1];
for(int i=19; i>=0; i--){
if(p[cur][i].ff>=l){
sum+=p[cur][i].ss;
cur=p[cur][i].ff;
}
}
sum+=comp[cur]*(cur-l+1);
if(dp[l]+comp[cur]*d<0) cout<<-1<<endl;
else cout<<ans-sum<<endl;
}
}
signed main(){
// freopen("hps.in", "r", stdin);
// freopen("hps.out", "w", stdout);
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t=1;
// cin>>t;
while(t--){
solve();
cout<<endl;
}
return 0;
}
