// what is matter? never mind. 
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
//#pragma GCC target("sse,sse2,sse3,sse4,popcnt,abm,mmx,avx,avx2") 
#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
#define ll long long
typedef int iint;
#define int long long
#define ull unsigned long long
#define SZ(x) ((int)((x).size()))
#define ALL(x) (x).begin(),(x).end()
using namespace std;
inline int read()
{
    char c=getchar();int x=0;bool f=0;
    for(;!isdigit(c);c=getchar())f^=!(c^45);
    for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
    if(f)x=-x;return x;
}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;

#define maxn 200005
#define inf 0x3f3f3f3f

bool mbe;

int n,m;

struct node{
	int x,v,op;
}a[maxn];

#define N 60*maxn
iint ls[N],rs[N],rt,tot;
int sum[N],tag[N];
iint stk[N],tp;
int V;
bool med;

int newn(){
	int u=(tp?stk[tp--]:++tot);
	assert(u<N-5);
	ls[u]=rs[u]=sum[u]=tag[u]=0;
	return u;
}
void rub(int p){
	stk[++tp]=p;
}
void pt(int p,int v,int len){
	tag[p]+=v;
	sum[p]+=v*len;
}
void down(int p,int len){
	if(!tag[p])return;
	if(!ls[p])ls[p]=newn();
	if(!rs[p])rs[p]=newn();
	pt(ls[p],tag[p],(len+1)/2),pt(rs[p],tag[p],len/2),tag[p]=0;
}
void up(int p){
	sum[p]=sum[ls[p]]+sum[rs[p]];
}
void add(iint&p,int l,int r,int ql,int qr,int v){
	if(!p) p=newn();
	if(l>=ql && r<=qr)return pt(p,v,r-l+1);
	int mid=l+r>>1; down(p,r-l+1);
	if(ql<=mid) add(ls[p],l,mid,ql,qr,v);
	if(qr>mid) add(rs[p],mid+1,r,ql,qr,v);
	up(p);
}
int ask(iint&p,int l,int r,int qr){
	if(!p||!sum[p])return 0;
	if(tag[p]>0)return 1;
	int mid=l+r>>1;
	if(qr<=mid) return ask(ls[p],l,mid,qr);
	if(sum[ls[p]]) return 1;
	return ask(rs[p],mid+1,r,qr);
}
void del(iint&p,int l,int r,int &v){
	if(!v || !sum[p] || !p)return;
	if(sum[p]<=v){
//		cout<<"DEL "<<rt<<" "<<l<<" "<<r<<" "<<sum[p]<<"\n";
		v-=sum[p],sum[p]=tag[p]=0;
		rub(p),p=0;
		return;
	}
	if(l==r){
//		cout<<"DEL1 "<<l<<" "<<v<<"\n";
		sum[p]-=v,v=0;
		return;
	}
	int mid=l+r>>1; down(p,r-l+1);
	del(ls[p],l,mid,v);
	del(rs[p],mid+1,r,v);
	up(p);
	if(!sum[p]) rub(p),p=0;
}

bool chk(int tim)
{
	cerr<<"chk "<<tim<<"\n";
	rt=tot=tp=0;
	For(i,1,n+m){
		if(a[i].op==0){
			if(a[i].v>=tim) continue;
			int L=a[i].x+a[i].v,R=a[i].x+tim-1;
//			cout<<"need "<<a[i].x<<" "<<L<<" "<<R<<"\n";
			add(rt,0,V,L,R,1);
		}else{
//			cout<<"GO "<<a[i].x<<" "<<a[i].v<<"\n";
			int o=0;
			if(a[i].x>0) o=ask(rt,0,V,a[i].x-1);
			if(o) return 0;
			int now=a[i].v;
			del(rt,0,V,now);
		}
	}
//	cout<<"OK "<<rt<<" "<<sum[rt]<<"\n";
	if(sum[rt])return 0;
	return 1;
}

signed main()
{
	//freopen("zecevi.in.3a","r",stdin);
//	freopen("qwq.out","w",stdout);
	cerr<<(1.0*(&mbe-&med)/1024576.0)<<"\n";
	n=read(),m=read();
	int up=0;
	For(i,1,n)a[i].x=read(),a[i].v=read(),a[i].op=0,up+=a[i].v;
	For(i,n+1,n+m)a[i].x=read(),a[i].v=read(),a[i].op=1,up+=a[i].v;
	up/=n;
//	cout<<"up "<<up<<"\n";
	sort(a+1,a+n+m+1,[&](node x,node y){
		if(x.x!=y.x)return x.x<y.x;
		return x.op<y.op;
	});
	V=up+inf;
	int l=0,r=up,res=0;
//	chk(48772599075036);return 0;
	while(l<=r){
		int mid=l+r>>1;
		if(chk(mid))res=mid,l=mid+1;
		else r=mid-1;
	}
	cout<<res;
	return 0;
}
/*
2 3 1
1 3
4 2 3
0 1 2
*/