60pts求调

#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,m;
set<pair<int,int>> e;
int fa[1000005];
int in[1000005];
int out[1000005];
int sum[1000005];
int findfa(int x){return (fa[x]==x)?(x):(fa[x]=findfa(fa[x]));}
void update(int &n,int u,int v){
    if(e.find({u,v})==e.end()){
        e.insert({u,v});
        n=max({n,u,v});
        in[v]++;
        out[u]++;
        fa[u]=u;
        fa[v]=v;
    }
}
void merge(pair<int,int> now){
    int u=now.first,v=now.second;
    int fau=findfa(u);
    int fav=findfa(v);
    fa[fau]=fav;
}
signed main(){
    cin>>m;
    for(int i=1;i<=m;i++){
        int u,v;
        cin>>u>>v;
        update(n,u,v);
    }
    for(auto now:e){
        merge(now);
    }
    int one=0;
    for(int i=0;i<=n;i++){
        if(fa[i]==i){
            one++;
        }
        if(out[i]>in[i]){
            int fai=findfa(i);
            sum[fai]+=out[i]-in[i];    
        }
    }
    int ans=one+e.size();
    for(int i=0;i<=n;i++){
        if(fa[i]==i&&sum[i]!=0){
            ans+=sum[i]-1;
        }
    }
    cout<<ans;
    return 0;
}