#include<bits/stdc++.h>
#define fi first
#define se second
#define ll long long
#define pb push_back
using namespace std;
ll n,D,q,a[300005],du[300005],b[300005],f[300005];
ll minn[25][300005];
bool sub2=true;
int get(int l,int r)
{
int k=__lg(r-l+1);
return min(minn[k][l],minn[k][r-(1<<(k))+1]);
}
int main()
{
ios::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
// freopen(".INP","r",stdin);
// freopen(".OUT","w",stdout);
cin>>n>>D;
for(int i=1;i<=n;i++)
{
cin>>a[i];
if(a[i]==1) b[i]=b[i-1]+1;
else b[i]=0;
f[i]=f[i-1]+a[i];
}
for(int i= 1;i<= n;i++)
minn[0][i] = a[i];
for(int j=1;j<= 20;j++)
{
for(int i= 1;i<= n - (1 << j) + 1;i++)
minn[j][i] = min(minn[j - 1][i], minn[j - 1][i + (1 << (j - 1))]);
}
cin>>q;
while(q--)
{
int l,r;
cin>>l>>r;
int d=l,c=r,vt=-1;
while(d<=c)
{
int mid=(d+c)>> 1;
if(get(mid,r))
{
vt=mid;
c=mid-1;
}
else
d=mid+1;
}
if(vt<0)
{
if(f[r] - f[l - 1] > 0)
{
if(D > 1)
cout << "-1\n";
else
cout << f[r] - f[l - 1] << "\n";
}
else
cout << "0\n";
}
else
{
int res = f[r] - f[l - 1] - (r - vt + 1);
if(res > 0)
{
if(D > 1)
cout << "-1\n";
else
cout << res << "\n";
}
else
cout << res << "\n";
}
}
return 0;
}
