struct Edge{    int from,to,cap,flow,cost;            Edge(int u,int v,int c,int f,int w):        from(u),to(v),cap(c),flow(f),cost(w)        {}};int n,m;vector<Edge> edges;vector<int> G[maxn];int inq[maxn];int d[maxn];int p[maxn];int a[maxn];void init(int n){    //this->n=n;    粉书上原版有这一句，但明显会报错。感觉去掉也没什么影响...    for (int i=0;i<n;i++)        G[i].clear();    edges.clear();}void AddEdge(int from,int to,int cap,int cost){    edges.push_back(Edge(from,to,cap,0,cost));    edges.push_back(Edge(to,from,0,0,-cost));    m=edges.size();    G[from].push_back(m-2);    G[to].push_back(m-1);}bool BellmanFord(int s,int t,int &flow,long long &cost)        //用队列优化过，感觉和SPFA一样了{    for (int i=0;i<n;i++)   d[i]=INF;    memset(inq,0,sizeof(inq));    d[s]=0;     inq[s]=1;       p[s]=0;     a[s]=INF;        queue<int> Q;    Q.push(s);    while (!Q.empty())    {        int u=Q.front();        Q.pop();        inq[u]=0;        for (int i=0;i<G[u].size;i++)        {            Edge& e=edges[G[u][i]];            if (e.cap>e.flow && d[e.to]>d[u]+e.cost())            {                d[e.to]=d[u]+e.cost;                p[e.to]=G[u][i];                a[e.to]=min(a[u],e.cap-e.flow);                if (!inq[e.to])                     {                    Q.push(e.to);                    inq[e.to]=1;                }            }        }    }    if (d[t]==INF)      return false;    flow+=a[t];    cost+=(long long)d[t] * (long long)a[t];    for (int u=t;u!=s;u=edges[p[u]].from)    {        edges[p[u]].flow+=a[t];        edges[p[u]^1].flow-=a[t];    }    return true;}    int MCMF(int s,int t,long long& cost)        //s:起点；t:汇点；{    int flow=0;     cost=0;            //flow:求出来的最大流      cost:求出来的费用    while (BellmanFord(s,t,flow,cost));    return flow;}