Shared code

#include<iostream>
#include<cstring>
#include<vector>
#include<queue>
#include<array>
#include<algorithm>

using namespace std;
int graph[1002][1002],par[1002],edges[1002][1002];
bool vis[1002];
bool bfs(){
int u=0;
queue<int>que;
que.push(u);
for(int i=0;i<=1001;i++)vis[i]=0;
while(!que.empty() ){
  u=que.front();
  que.pop();
  if(vis[u])continue;
  vis[u]=true;
  for(int v=0;v<=1001;v++){
    if(!vis[v] and graph[u][v]>0){
      par[v]=u;
      que.push(v);
    }
    }
  }
return vis[1001];
}
int main(){
  int n,m,k,a,b;
  cin>>n>>m>>k;
  while(k--){
    cin>>a>>b;
    b+=500;
   graph[a][b]=1;
   graph[0][a]=1;
   graph[b][1001]=1;
   edges[a][b]=1;
  }
  int cnt=0;
  while(bfs()){
    a=1001;
    cnt++;
    while(a!=0){
      graph[par[a]][a]--;
      graph[a][par[a]]++;
      a=par[a];
    }
  }
  cout<<cnt<<endl;
  vector<array<int,2>>ans;
  for(int i=1;i<=n;i++){
    for(int j=1;j<=m;j++){
      if(!graph[i][j+500] and edges[i][j+500]){
        cout<<i<<" "<<j<<endl;
      }
    }
  }
  return 0;
}