#include <bits/stdc++.h>
using namespace std;

#define int long long

const int N=3e5+5;
const int INF=1e18;

vector<pair<int,int> > que[N];
pair<int,int> stk[N];
int a[N], val[N], sum[N];
int ans[N];

signed main()
{
	int n,d;
	cin >> n >> d;
	for(int i=1;i<=n;i++)
		scanf("%lld",&a[i]);

	int q;
	cin >> q;
	for(int i=1;i<=q;i++)
	{
		int l,r;
		scanf("%lld %lld",&l,&r);
		que[r].push_back(make_pair(l,i));
	}

	for(int i=n-1;i>=1;i--)
	{
		val[i]=val[i+1];
		if(a[i]>=a[i+1])
			val[i] += (a[i]-a[i+1]+d-1)/d;
		else
			val[i] -= (a[i+1]-a[i])/d;
	}

	for(int i=1;i<=n;i++)
		sum[i]=sum[i-1]+val[i];

	int top=0;
	stk[++top]=make_pair(0,0);
	for (int i = 1; i <= n; i++)
	{
		while(top>1 && val[stk[top].first]>=val[i])
			top--;

		stk[++top]=make_pair(i,stk[top].second+val[i]*(i-stk[top].first));

		for(auto x:que[i])
		{
			int l=x.first, id=x.second, pos=lower_bound(stk+1,stk+top+1,make_pair(l,-INF))-stk;
			ans[id]=stk[top].second-stk[pos-1].second-val[stk[pos].first]*(l-1-stk[pos-1].first);
			ans[id]=sum[i]-sum[l-1]-ans[id];
			if (a[l]<d*(val[l]-val[stk[pos].first]))
				ans[id]=-1;
		}
	}

	for(int i=1;i<=q;i++)
		printf("%lld\n",ans[i]);
	return 0;
}