785B - Anton and Classes - CodeForces Solution

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

#define    debug(x)            cout<< #x << " = " << x <<endl;
#define    endl                "\n"
typedef    long long           ll;



void solve() {
    int n; cin >> n;
    vector< int > ca, cb;
    vector< int > pa, pb;

    for(int i = 0; i < n; i ++) {
        int a, b; cin >> a >> b;
        ca.push_back(a); cb.push_back(b);
    }
    int m; cin >> m;
    for(int i = 0; i < m; i ++) {
        int a, b; cin >> a >> b;
        pa.push_back(a); pb.push_back(b);
    }
    sort(ca.begin(), ca.end());
    sort(pa.begin(), pa.end());
    sort(cb.begin(), cb.end());
    sort(pb.begin(), pb.end());

    int ans = pa[m - 1] - cb[0];
    ans = max(ans, ca[n - 1] - pb[0]);
    ans = max(ans, 0);
    cout<< ans << endl;


}


int32_t main() {

    ios::sync_with_stdio(false); cin.tie(0);
    int T = 1;
    //cin >> T;
    while(T --) {
        solve();
    }
    return 0;

}