rt,调不动了（

#include<bits/stdc++.h>
using namespace std;
int n,m;
int s,t;
const int Max=605;
const int inf=1e9+7;
using pii=pair<int,int>;
struct Edge
{
    int v;
    int flow;
    int cost;
    int id;
};
vector<Edge> edge[Max];
void addedge(int u,int v,int flow,int cost)
{
    int idu=edge[u].size();
    int idv=edge[v].size();
    edge[u].push_back((Edge){v,flow,cost,idv});
    edge[v].push_back((Edge){u,0,-cost,idu});
}
int h[Max];
bool vis[Max];
void spfa()
{
    queue<int> q;
    fill(h,h+t+1,inf);
    h[s]=0;
    q.push(s);
    vis[s]=1;
    while(!q.empty())
    {
        int u=q.front();
        q.pop();
        vis[u]=0;
        for(auto e:edge[u])
        {
            int v=e.v;
            if(e.flow&&h[v]>h[u]+e.cost)
            {
                h[v]=h[u]+e.cost;
                if(!vis[u])
                {
                    vis[u]=1;
                    q.push(u);
                }
            }
        }
    }
}
int dis[Max];
pii pre[Max];
bool dij()
{
    priority_queue<pii,vector<pii>,greater<pii> > q;
    fill(vis,vis+t+1,0);
    fill(dis,dis+t+1,inf);
    dis[s]=0;
    q.push((pii){dis[s],s});
    while(!q.empty())
    {
        int u=q.top().second;
        q.pop();
        if(vis[u])
        {
            continue;
        }
        vis[u]=1;
        for(int i=0;i<edge[u].size();i++)
        {
            const Edge e=edge[u][i];
            if(!e.flow)
            {
                continue;
            }
            int v=e.v;
            int w=e.cost+h[u]-h[v];
            if(dis[v]>dis[u]+w)
            {
                dis[v]=dis[u]+w;
                pre[v]=(pii){u,i};
                q.push((pii){dis[v],v});
            }
        }
    }
    return dis[t]^inf;
}
int mcmf()
{
    spfa();
    int cost=0,flow;
    while(dij())
    {
        for(int i=1;i<=n;i++)
        {
            h[i]+=dis[i];
        }
        flow=inf;
        for(int cur=t;cur^s;cur=pre[cur].first)
        {
            flow=min(flow,edge[pre[cur].first][pre[cur].second].flow);
        }
        for(int cur=t;cur^s;cur=pre[cur].first)
        {
            auto &e=edge[pre[cur].first][pre[cur].second];
            auto &fe=edge[e.v][e.id];
            e.flow-=flow;
            fe.flow+=flow;
            cost+=e.cost*flow;
        }
    }
    return cost;
}
int main()
{
    cin>>m>>n;
    s=0,t=n*m+n+1;
    for(int i=1;i<=n;i++)
    {
        addedge(s,i,1,0);
    }
    for(int i=1;i<=m;i++)
    {
        for(int j=1;j<=n;j++)
        {
            addedge(i*n+j,t,1,0);
        }
    }
    for(int i=1;i<=n;i++)
    {
        for(int j=1;j<=m;j++)
        {
            int cost;
            cin>>cost;
            for(int k=1;k<=n;k++)
            {
                addedge(i,j*n+k,1,cost*k);
            }
        }
    }
    cout<<fixed<<setprecision(2)<<1.0*mcmf()/n;
    return 0;
}