#include <bits/stdc++.h>
// #include <ext/rope>
// #include <ext/pb_ds/assoc_container.hpp>
// using namespace __gnu_pbds;
// using namespace __gnu_cxx;
using namespace std;
// #define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define ll long long
#define ull unsigned long long
#define ld long double
#define pb push_back
#define bit(mask, i) ((mask >> i) & 1)
#define el '\n'
#define F first
#define S second
template <class X, class Y> bool maximize(X &x, const Y &y) { return (x < y ? x = y, 1 : 0); }
template <class X, class Y> bool minimize(X &x, const Y &y) { return (x > y ? x = y, 1 : 0); }
const int INF = 1e9;
const ll LINF = 1e18;
const int MOD = 1e9 + 7;
const int MULTI = 0;
const ld eps = 1e-9;
const int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0}; // R D L U
const int ddx[4] = {-1, 1, 1, -1}, ddy[4] = {1, 1, -1, -1}; // UR DR DL UL
const char cx[4] = {'R', 'D', 'L', 'U'};
const ll base = 31;
const int nMOD = 2;
const ll mods[] = {(ll)1e9 + 10777, (ll)1e9 + 19777, (ll)1e9 + 3, (ll)1e9 + 3777};
const int N = 1e5 + 5;
int n, m, c[N], pos[N], pref[N];
struct pic {
int s, v, id;
} p[N];
void solve() {
cin >> n >> m;
for (int i = 1; i <= n; ++i) {
cin >> p[i].s >> p[i].v;
p[i].id = i;
}
for (int i = 1; i <= m; ++i)
cin >> c[i];
sort(c + 1, c + 1 + m);
sort(p + 1, p + 1 + n, [&](pic A, pic B){
return A.v < B.v;
});
for (int i = 1; i <= n; ++i)
pos[p[i].id] = i;
sort(p + 1, p + 1 + n, [&](pic A, pic B){
return A.s < B.s;
});
set<int> s;
for (int i = 1; i <= n; ++i) s.insert(i);
int ptr = n, cur = n + 1, res = 0;
for (int i = m; i >= 1; --i) {
while (ptr > 0 && p[ptr].s > c[i]) s.erase(pos[p[ptr--].id]);
auto it = s.lower_bound(cur);
if (it == s.begin()) break;
it--;
cur = *it; res++;
s.erase(it);
}
cout << res;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
if (!MULTI) solve();
else {
int test; cin >> test;
while (test--) solve();
}
return 0;
}
