#include <bits/stdc++.h>
using namespace std;
using ll = long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
#define pb push_back
#define ff first
#define ss second
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int n; cin>>n;
vector<int> a(n + 1), c(n + 1), f[n + 1];
for (int i = 1; i <= n; i++){
cin>>a[i]>>c[i];
f[a[i]].pb(c[i]);
}
for (int i = 1; i <= n; i++){
reverse(f[i].begin(), f[i].end());
}
vector<int> b(n + 1), d(n + 1);
for (int i = 1; i <= n; i++){
cin>>b[i]>>d[i];
}
vector<int> s(n + 1);
int out = n;
for (int i = n; i > 0; i--){
int x = b[i];
if (s[x] != f[x].size() && f[x][s[x]] <= d[i]){
out--;
s[x]++;
}
}
int out1 = n, tt = 1;
vector<int> p = {0};
for (int i = 1; i <= n; i++){
tt *= i;
p.pb(i);
}
while (tt--){
bool I = 0;
for (int i = 1; i <= n; i++){
if (d[p[i]] < c[i]){
I = 1;
break;
}
}
if (!I){
int cc = 0;
for (int i = 1; i <= n; i++){
cc += (a[i] != b[p[i]]);
}
out1 = min(out1, cc);
}
next_permutation(p.begin() + 1, p.end());
}
assert(out == out1);
cout<<out<<"\n";
// cout<<out<<" "<<out1<<"\n";
}
