#include <bits/stdc++.h>
using namespace std;
#define int long long
#define rep(i,a,b) for (int i = a; i <= b; ++i)
#define per(i,a,b) for (int i = a; i >= b; --i)
#define pii pair<int,int>
#define fi first
#define se second
#define all(v) (v).begin(), (v).end()
#define pb push_back
const int MAXN = 1e5 + 10;
struct Range {
int l, r;
Range(int x, int y) {
l = x;
r = y;
}
Range(int x) { l = r = x; }
Range() {
l = INT_MAX;
r = INT_MIN;
}
Range operator|(Range a) { return Range(min(l, a.l), max(r, a.r)); }
void operator|=(Range a) {
l = min(l, a.l);
r = max(r, a.r);
}
};
struct Seg3{
vector<Range> v;
int c;
void update(int x, Range y) {
x += 1 << c;
while (x) {
v[x] |= y;
x /= 2;
}
}
Range calc(int x) { return v[x+(1<<c)]; }
Range calc(int l, int r) {
l += 1 << c;
r += 1 << c;
Range x;
while (l<=r) {
x |= v[l];
x |= v[r];
l = (l + 1)/2;
r = (r - 1)/2;
}
return x;
}
Range calc(Range x) { return calc(x.l, x.r); }
Seg3() {}
Seg3(int n) {
c = 0;
while ((1 << c) < n) c++;
v.resize(1 << c + 1);
}
};
int n,m,k,q;
Range R[MAXN];
Seg3 seg[18];
int query(int s, int t) {
int cnt = 0;
Range p = Range(s);
per(i, 17, 0) {
Range q = seg[i].calc(p);
if (!(q.l <= t && t <= q.r)) {
p = q;
cnt += 1 << i;
}
}
if (cnt == (1 << 18) - 1) return -1;
else return cnt + 1;
}
int32_t main() {
ios_base::sync_with_stdio(0); cin.tie(nullptr);
cin >> n >> k >> m;
rep(i,0,17) seg[i] = Seg3(n);
rep(i,0,n-1) R[i] = Range(i);
rep(i,1,m) {
int a,b;cin >> a >> b;
R[a-1] |= Range(b-1);
}
deque<pii> dq;
rep(i,0,n-1) {
while (!dq.empty() && dq.back().fi < R[i].r) dq.pop_back();
dq.push_back({R[i].r,i+k-1});
seg[0].update(i, Range(dq.front().fi));
while (!dq.empty() && dq.front().se <= i) dq.pop_front();
}
dq.clear();
per(i,n-1,0) {
while(!dq.empty() && dq.back().fi > R[i].l) dq.pop_back();
dq.push_back({R[i].l,i-k+1});
seg[0].update(i, Range(dq.front().fi));
while (!dq.empty() && dq.front().se >= i) dq.pop_front();
}
rep(i,1,17) {
rep(j,0,n-1) {
seg[i].update(j, seg[i-1].calc(seg[i-1].calc(j)));
}
}
cin >> q;
while (q--) {
int u,v;cin >> u >> v;
u--;v--;
cout << query(u,v) << '\n';
}
}
