#include <bits/stdc++.h>
using namespace std;
#define sz(x) (int)x.size()
#define MASK(i) ((1LL) << (i))
#define all(x) x.begin(), x.end()
#define BIT(x, i) ((x) >> (i) & (1LL))
#define dbg(...) cerr << "#" << __LINE__ << ":[" << #__VA_ARGS__ \
<< "] = [" ,DBG(__VA_ARGS__)
string to_string(const string& s) { return '"' + s + '"'; }
void DBG() { cerr << "]" << endl; }
template<class H, class... T> void DBG(H h, T... t) {
cerr << to_string(h); if(sizeof...(t)) cerr << ", "; DBG(t...);
}
template <class T>
inline bool maximize(T &a, const T &b) { return (a < b ? (a = b) : 0); }
template <class T>
inline bool minimize(T &a, const T &b) { return (a > b ? (a = b) : 0); }
const int MAXN = 1e5 + 6;
const int INF = 1e9;
const int MOD = 1e9 + 7;
int nPic, nFrame;
int frame_size[MAXN], dp[1005][1005];
struct dat {
int Size, Val;
} pic[MAXN];
void solve() {
cin >> nPic >> nFrame;
for (int i = 1; i <= nPic; i++) {
cin >> pic[i].Size >> pic[i].Val;
}
for (int i = 1; i <= nFrame; i++) cin >> frame_size[i];
sort(pic + 1, pic + nPic + 1, [] (dat pic1, dat pic2) {
if (pic1.Val == pic2.Val) return pic1.Size < pic2.Size;
return pic1.Val < pic2.Val;
});
sort(frame_size + 1, frame_size + nFrame + 1);
int res = 0, j = nFrame;
for (int i = nPic; i >= 1; --i) {
if (pic[i].Size <= frame_size[j]) {
++res;
--j;
}
if (j == 0) break;
}
cout << res;
}
#define TASK ""
int main() {
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
//freopen(TASK".inp", "r", stdin);
//freopen(TASK".out", "w", stdout);
int ntest = 1;
//cin >> ntest;
while (ntest--) solve();
return 0;
}
//612
