#include <bits/stdc++.h>
#define int long long
const int maxn = 3e5;
int N, D, Q;
int C[maxn + 5], L[maxn + 5], R[maxn + 5];
namespace SUB1 {
int d[4000], diff[4000], x[4000];
void solve() {
for (int i = 1; i < N; ++i) diff[i] = C[i] - C[i + 1];
for (int _ = 1; _ <= Q; ++_) {
int l = L[_], r = R[_], ans = 0;
for (int i = l; i <= r; ++i) {
d[i] = 0;
x[i] = 0;
}
for (int i = r - 1; i >= l; --i) {
if (d[i] < diff[i]) {
int cnt = (diff[i] - d[i] + D - 1) / D;
x[i] += cnt * D; x[i + 1] -= cnt * D;
ans += cnt;
d[i] += cnt * D;
d[i - 1] -= cnt * D;
}
x[i + 1] += d[i] - diff[i];
}
for (int i = l + 1; i <= r; ++i)
x[i] += x[i - 1];
bool ok = true;
for (int i = l; i <= r; ++i) {
ok &= (x[i] <= C[i]);
}
std::cout << (ok ? ans : -1) << '\n';
}
}
};
namespace SUB2 {
int pref[maxn + 5];
bool check_sub() {
bool ok = true;
for (int i = 1; i <= N; ++i)
ok &= (C[i] <= 1);
return ok;
}
void solve() {
for (int i = 1; i <= N; ++i)
pref[i] = pref[i - 1] + C[i];
for (int _ = 1; _ <= Q; ++_) {
int l = L[_], r = R[_];
int cnt = pref[r] - pref[l - 1];
int lb = l, rb = r, mn = r + 1;
while (lb <= rb) {
int mid = (lb + rb) >> 1;
if (pref[r] - pref[mid - 1] == r - mid + 1) {
mn = mid;
rb = mid - 1;
} else {
lb = mid + 1;
}
}
int ans = cnt - (r - mn + 1);
if (ans) {
std::cout << (D == 1 ? ans : -1) << '\n';
} else {
std::cout << 0 << '\n';
}
}
}
};
signed main() {
// freopen("fish3.inp", "r", stdin);
std::cin.tie(0)->sync_with_stdio(0);
std::cin >> N >> D;
for (int i = 1; i <= N; ++i) std::cin >> C[i];
std::cin >> Q;
for (int i = 1; i <= Q; ++i) std::cin >> L[i] >> R[i];
if (SUB2::check_sub()) {
SUB2::solve();
return 0;
}
SUB1::solve();
return 0;
}
