Bus Station

/*
    Task        : _example
    Author      : Phumipat C. [MAGCARI]
    Language    : C++
*/
#include<bits/stdc++.h>
using namespace std;
struct A{
    int st,en;
    bool operator < (const A&o) const{
        if(st != o.st)  return st < o.st;
        else            return en < o.en;
    }
};
A a[100010];
int main(){
    int n,m,q;
    cin >> n >> m >> q;
    for(int i=1;i<=n;i++){
        cin >> a[i].st >> a[i].en;
    }
    sort(a+1,a+n+1);
    while(q--){
        int startPoint,endPoint;
        cin >> startPoint >> endPoint;
        int now = 1,mx = 0;
        while(now<=n && a[now].st <= startPoint){
            mx = max(mx,a[now].en);
            now++;
        }
        if(mx < startPoint){
            cout << "-1\n";
            continue;
        }
        int cnt = 1;
        while(now <= n && a[now].st <= mx && mx < endPoint){
            int newMx = mx;
            while(now <= n && a[now].st <= mx && newMx < endPoint){
                newMx = max(newMx,a[now].en);
                now++;
            }
            mx = newMx;
            cnt++;
        }
        if(mx >= endPoint)
            cout << cnt << '\n';
        else
            cout << "-1\n";
    }
    return 0;
}