#include <bits/stdc++.h> #define pb push_back #define endl ("\n") #define all(aa) aa.begin(), aa.end() typedef long long ll; using namespace std; struct segTree{ int n; vector<int> t; segTree(int n) : n(n), t(4 * n, INT_MAX){} void upd(int u, int tl, int tr, int pos, int val){ if(tl == tr){ t[u] = val; return; } int tm = (tl + tr) / 2; if(pos <= tm) upd(u * 2, tl, tm, pos, val); else upd(u * 2 + 1, tm + 1, tr, pos, val); t[u] = min(t[u * 2], t[u * 2 + 1]); } void upd(int pos, int val){ upd(1, 0, n - 1, pos, val); } int walk(int u, int tl, int tr, int x){ if(tl == tr){ return tl; } int tm = (tl + tr) / 2; if(t[u * 2 + 1] <= x) return walk(u * 2 + 1, tm + 1, tr, x); return walk(u * 2, tl, tm, x); } int walk(int x){ return walk(1, 0, n - 1, x); } }; int main(){ int n, m; cin >> n >> m; vector<array<int, 2>> a(n); vector<int> c(m); for(int i = 0; i < n; i++) cin >> a[i][1] >> a[i][0]; for(int i = 0; i < m; i++) cin >> c[i]; sort(all(a)); segTree st(n); for(int i = 0; i < n; i++){ st.upd(i, a[i][1]); } sort(all(c)); int ans = 0; int r = n; for(int i = m - 1; i >= 0; i--){ int j = st.walk(c[i]); if(a[j][1] > c[i]) continue; while(j < r){ r--; st.upd(r, INT_MAX); } ans++; } cout << ans << endl; }