Why WA 70 Pts

#include <bits/stdc++.h>
using namespace std;
int n,k;
struct node{
    int l,r;
};
bool cmp(node a, node b){
    return a.r<b.r;
}
bool cmp2(node a, node b){
    return a.l<b.l;
}
node cow[1500];
node spf[1500];
int main(){
    cin >> n >> k;
    for (int i=1; i<=n; i++){
        cin >> cow[i].l >> cow[i].r;
    }
    for (int i=1; i<=k; i++){
        cin >> spf[i].l >> spf[i].r;
    }
    sort(cow+1,cow+n+1,cmp);
    sort(spf+1,spf+k+1,cmp2);
    int ans=0;
    for (int i=1; i<=n; i++){
        for (int j=1; j<=k; j++){
            //cout << cow[i].l << " " <<  cow[i].r << " " <<  spf[j].l << " " << spf[j].r << endl;
            if (cow[i].l<=spf[j].l && spf[j].l<=cow[i].r && spf[j].r>0){
                ans++;
                spf[j].r--;
                break;
            }
        }
    }
    cout << ans;
}