/*
Author: Nguyen Chi Thanh - High School for the Gifted - VNU.HCM (i2528)
*/
#include <bits/stdc++.h>
using namespace std;
/* START OF TEMPALTE */
// #define int long long
#define ll long long
#define ull unsigned long long
#define ld long double
#define pii pair<int, int>
#define pll pair<ll, ll>
#define fi first
#define se second
#define __builtin_popcount __builtin_popcountll
#define all(x) (x).begin(), (x).end()
#define BIT(x, i) (((x) >> (i)) & 1)
#define MASK(x) (1ll << (x))
#define SZ(a) ((int32_t)a.size())
#define debug(a, l, r) {for (int _i = (l); _i <= (r); ++_i) cout << (a)[_i] << ' '; cout << '\n';}
template<class X, class Y>
bool minimize(X &x, const Y &y) {
if (x > y) {
x = y;
return true;
} else return false;
}
template<class X, class Y>
bool maximize(X &x, const Y &y) {
if (x < y) {
x = y;
return true;
} else return false;
}
/* END OF TEMPALTE */
void solve() {
int n, m; cin >> n >> m;
vector<pii> pictures;
vector<int> frames;
for (int i = 0; i < n; ++i) {
int s, v; cin >> s >> v;
pictures.push_back({s, v});
}
for (int i = 0; i < m; ++i) {
int c; cin >> c;
frames.push_back(c);
}
sort(all(pictures), [&] (pii x, pii y) {
if (x.se == y.se) return x.fi > y.fi;
return x.se > y.se;
});
sort(all(frames), greater<int>());
int res = 0;
for (int i = 0, j = 0; i < n && j < m; ++i) {
if (frames[j] >= pictures[i].fi) {
++j; ++res;
}
}
cout << res;
}
signed main() {
#ifdef NCTHANH
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(0);
cin.tie(nullptr); cout.tie(nullptr);
solve();
return 0;
}
