#include<bits/stdc++.h> using namespace std; #define ll long long #define fi first #define se second const bool Multitest = 0; const int N = 1e5 + 10; pair<int, int> a[N]; int b[N]; int n, m; void maximize(int& a, int b) { if(a < b) a = b; } namespace sub1 { const int Nsub = 1e3 + 10; int dp[Nsub][Nsub]; void solve() { sort(a + 1, a + 1 + n); sort(b + 1, b + 1 + m); for(int i = 1 ; i <= m ; i++) { for(int j = 1 ; j <= n ; j++) { dp[i][j] = dp[i - 1][j - 1] + (a[j].se <= b[i]); maximize(dp[i][j], dp[i][j - 1]); } } cout << dp[m][n]; } } namespace sub3 { int dp[N]; pair<int, int> c[N]; struct ST { int t[4 * N]; void update(int id, int l, int r, int u, int v) { if(r < u || u < l) return; if(l == r) { t[id] = v; return; } int mid = (l + r) >> 1; update(id * 2, l, mid, u, v); update(id * 2 + 1, mid + 1, r, u, v); t[id] = max(t[id * 2], t[id * 2 + 1]); } int get(int id, int l, int r, int u, int v) { if(r < u || v < l) return 0; if(u <= l && r <= v) return t[id]; int mid = (l + r) >> 1; return max(get(id * 2, l, mid, u, v), get(id * 2 + 1, mid + 1, r, u, v)); } }; ST st; void solve() { sort(a + 1, a + 1 + n); sort(b + 1, b + 1 + m); for(int i = 1 ; i <= n ; i++) c[i].se = a[i].fi, c[i].fi = a[i].se; sort(c + 1, c + 1 + n); int ptr = 0; set<pair<int, int>> s; for(int i = 1 ; i <= m ; i++) { while(ptr < n && c[ptr + 1].fi <= b[i]) { ptr++; s.insert({a[ptr].se, ptr}); } if(s.size() != 0) { pair<int, int> x = *s.begin(); s.erase(x); dp[i] = st.get(1, 1, n, 1, x.se - 1) + 1; st.update(1, 1, n, i, dp[i]); } } cout << st.get(1, 1, n, 1, n); } } void work() { cin >> n >> m; for(int i = 1 ; i <= n ; i++) { cin >> a[i].se >> a[i].fi; } for(int i = 1 ; i <= m ; i++) cin >> b[i]; if(n <= 1000 && m <= 1000) return sub1::solve(); sub3::solve(); } int main() { ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0); int q = 1; if(Multitest) cin >> q; while(q--) work(); }