[題解]人員調動

a130. 人員調動

#include <bits/stdc++.h>
#define ll long long
#define ld  long double
#define N 1005
#define FOR(i,n) for(int i=0;i<n;i++)
#define pii pair<int,int>
using namespace std;

void solve(){
    int wait[N][N];memset(wait,0,sizeof(wait));
    
    int m,ans = 0;cin>>m;
    for(int i=0;i<m;i++){
        int a,b;cin>>a>>b;
        if(wait[b][a]>0){
            ans++;wait[b][a]--;
        }
        else wait[a][b]++;
    }
    cout<<ans<<endl;
}

int main(){
    int t;cin>>t;
    while(t--){
        solve();
    }
}