339-chat-online.cpp

/*
 * Chat Online  [469B]
 * Problem:  https://codeforces.com/problemset/problem/469/B
 * Verdict:  ACCEPTED        Solved: 2021-01-17
 * Language: C++17 (GCC 7-32)
 * Runtime:  31 ms     Memory: 0 KB
 * Tags:     implementation
 * Author:   BidoTeima
 * Source:   https://codeforces.com/contest/469/submission/104602595
 */

#include <bits/stdc++.h>
using namespace std;
// Important functions and defines
/// BidoTeima legacy functions
typedef long long ll;
ll POW(ll a, ll b) {
   ll res = 1;
   while(b > 0) {
    if(b%2==1) res*=a;
    a*=a;
    b/=2;
   }
   return res;
}
ll sum_range2d(ll i, ll j, ll k, ll l, vector<vector<ll>>& sum) {
    return sum[k][l] - sum[k][j - 1] - sum[i - 1][l] + sum[i - 1][j - 1];
}
ll gcd(ll a, ll b) {
    return (b == 0 ? abs(a) : gcd(b, a % b));
}
ll dist(ll X1, ll Y1, ll X2, ll Y2) {
    return sqrt( POW(X1-X2, 2) + POW(Y1-Y2,2) );
}
bool intersect(pair<int, int> p1, pair<int, int> p2) {
  int x1 = p1.first, x2 = p1.second, y1 = p2.first, y2 = p2.second;
  return (x1 >= y1 && x1 <= y2) ||
         (x2 >= y1 && x2 <= y2) ||
         (y1 >= x1 && y1 <= x2) ||
         (y2 >= x1 && y2 <= x2);
}
bool isPrime(ll n) {
    for(ll i = 2; i * i <= n; i++) if(n%i==0) return false;
    return true;
}
/*vector<bool> prime(10000005, true);
void sievePrime(ll n)
{
    for (int p=2; p*p<=n; p++)
    {
        if (prime[p] == true)
        {
            for (int i=p*p; i<=n; i += p)
                prime[i] = false;
        }
    }
}*/
bool isVowel(char ch) {
    return ch == 'a' || ch == 'e' || ch == 'i' || ch == 'o' || ch == 'u';
}
/// End of BidoTeima legacy functions
#define SCD(t) scanf("%d",&t)
#define SCLD(t) scanf("%ld",&t)
#define SCLLD(t) scanf("%lld",&t)
#define all(cont) cont.begin(), cont.end()
#define rall(cont) cont.rbegin(), cont.rend()
#define f first
#define s second
#define fast ios::sync_with_stdio(0);cin.tie(0);cout.tie(0);
//Ends
int32_t main()
{
    ///freopen ("output.txt","w",stdout);
    ///freopen("input.txt", "r", stdin);
    fast
    int p, q, l, r;
    cin>>p>>q>>l>>r;
    pair<ll, ll> a[p], c[q];
    for(int i = 0; i < p; i++) {
        cin>>a[i].f>>a[i].s;
    }
    for(int i = 0; i < q; i++) {
        cin>>c[i].f>>c[i].s;
    }
    /// size a > size c
    ll ans = 0;
    bool is[1005];
    fill(is, is+1005, false);
    for(int i = 0; i < p; i++) {
        for(int j = 0; j < q; j++) {
            // i -> a, j -> c
            for(int x = l; x <= r; x++) {
                if(intersect(a[i], {c[j].f+x,c[j].s+x})) {
                    if(!is[x]) {
                        is[x]=true;
                        ++ans;
                    }
                }
            }
        }
    }
    cout<<ans;
    return 0;
}