#include<bits/stdc++.h>
using namespace std;
#define fi first
#define sc second
#define pii pair<int,int>
#define pb push_back
#define umap unordered_map
#define mset multiset
#define pq priority_queue
#define ull unsigned long long
#define i128 __int128
const int maxn=2e5+10;
pii p[maxn];
int a[maxn],b[maxn],c[maxn],n,m,maxx[maxn];
void solve(){
    cin>>n>>m;
    for(int i=1;i<=n;i++) cin>>p[i].fi>>p[i].sc;
    for(int i=1;i<=m;i++) cin>>a[i]>>b[i];
    sort(p+1,p+n+1);
    for(int i=1;i<=n;i++) c[i]=p[i].fi;
    for(int i=1;i<=n;i++) maxx[i]=max(maxx[i-1],p[i].sc);
    ull res=0;
    for(int i=1;i<=m;i++){
        int pos=upper_bound(c+1,c+n+1,a[i])-c-1;
        // cout<<pos<<" "<<maxx[pos]<<endl;
        res+=max(0,maxx[pos]-b[i]);
    }
    cout<<res<<endl;
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0),cout.tie(0);
    int t=1;
    // cin>>t;
    while(t--) solve();
    return 0;
}
/*
Samples
input:

output:

THINGS TODO:
检查freopen，尤其是后缀名
检查空间
检查调试语句是否全部注释
*/