#pragma GCC optimize("Ofast,unroll-loops")
#pragma GCC target("avx,avx2,sse,sse2,sse3,fma")
#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define fi first
#define se second
#define pb emplace_back
#define all(n) (n).begin(),(n).end()
#define mem(n,x) memset(n,x,sizeof(n))
#define IOS ios::sync_with_stdio(0),cin.tie(0)
#define pii pair<ll,ll>
#define vi vector<ll>
#define dbg(...) cerr<<#__VA_ARGS__<<" = ";_do(__VA_ARGS__);
#define int ll
template<typename A> void _do(A x){ cerr<<x<<"\n"; }
template<typename A, typename ...B> void _do(A x, B ...y){ cerr<<x<<", "; _do(y...);}

ll n,m;

ll area(pii x, pii y){
	if(x.fi > y.fi || x.se > y.se) return -100;
	return (y.fi - x.fi) * (y.se - x.se);
}

signed main(){
	IOS;
	cin>>n>>m;
	deque<pii> sell(n), buy(m);
	for(int i=0;i<n;i++){
		cin>>sell[i].fi>>sell[i].se;
	}
	for(int i=0;i<m;i++){
		cin>>buy[i].fi>>buy[i].se;
	}

	sort(all(sell));
	sort(all(buy));

	deque<pii> tmp;
	for(auto i:sell){
		if(tmp.size() && i.se > tmp.back().se) continue;
		tmp.pb(i);
	}
	sell = tmp;
	tmp.clear();
	for(auto i:buy){
		while(tmp.size() && i.se > tmp.back().se) tmp.pop_back();
		tmp.pb(i);
	}
	buy = tmp;
	
	deque<pii> dq;
	while(!sell.empty() && !buy.empty() && area(sell[0],buy[0]) <= 0){
		if(sell[0].fi >= buy[0].fi) buy.pop_front();
		else if(sell[0].se >= buy[0].se) sell.pop_front();
		else assert(false);
	}
	/* for(auto i:sell) cout<<i.fi<<" "<<i.se<<" "; cout<<'\n'; */
	/* for(auto i:buy) cout<<i.fi<<" "<<i.se<<" "; cout<<'\n'; */
	for(int i=0,siz=sell.size();i<siz;i++){
		while(dq.size()){
			auto &[pid,pl] = dq.back();
			if(area(sell[i],buy[pl]) <= area(sell[pid],buy[pl])) break;
			dq.pop_back();
		}
		if(dq.empty()){
			dq.pb(i,0);
		}
		else{
			int l = dq.back().se, r = buy.size(), pid = dq.back().fi;
			while(l<r){
				int m = (l+r)/2;
				ll cura = area(sell[i], buy[m]), prea = area(sell[pid], buy[m]);
				/* dbg(m, cura, prea); */
				if(cura < 0 && prea < 0){
					if(buy[m].fi < sell[i].fi) l = m + 1;
					else r = m;
				}
				else if(cura < 0 || prea >= cura) l = m + 1;
				else r = m;
			}
			if(l < buy.size() && area(sell[i], buy[l]) > 0) dq.pb(i,l);
		}
	}
	/* for(auto i:dq) cout<<i.fi<<" "<<i.se<<'\n'; */
	if(dq.empty()) return cout<<0<<'\n', 0;
	ll ans = 0;
	for(int i=0;i<buy.size();i++){
		while(dq.size() >= 2 && dq[1].se <= i) dq.pop_front();
		/* dbg(dq[0].fi, i); */
		ans = max(ans, area(sell[dq[0].fi], buy[i]));
	}
	cout<<ans<<'\n';
}