const int N = 1e3+5;
int Grid[N][N];

void DFS(int I,int J){
    // make sure (I,J) is marked visited
    Output(I,J);
    int nxt_i ,nxt_j;
    for(int i=0;i<4;i++){
        nxt_i=I+pos[i][0], nxt_j=J+pos[i][1];
        // check if out of range
        if(I_nxt_i_<1||nxt_i>1000||nxt_j<1||nxt_j>1000){
          continue;
        }
        // check if visited
        if(visited[nxt_i][nxt_j]) continue;
        visited[nxt_i][nxt_j]=true;
        DFS(nxt_i,nxt_j);
    }
}

int dir[4][2]={{0,1},{1,0},{0,-1},{-1,0}};

int cur_r ,cur_c ;
for(int i=0;i<4;i++){
    int nxt_r=cur_r+ dir[i][0] ;
    int nxt_c=cur_c+ dir[i][1] ; 

}

void DFS(int I,int J){
  // make sure (I,J) is marked visited
  Output(I,J);
  int nxt_i ,nxt_j;
  for(int i=0;i<4;i++){
    nxt_i=I+pos[i][0], nxt_j=J+pos[i][1];
    // check if out of range
    if(I_nxt_i_<1||nxt_i>1000||nxt_j<1||nxt_j>1000) continue;
    // check if visited
    if(visited[nxt_i][nxt_j]) continue;
    visited[nxt_i][nxt_j]=true;
    DFS(nxt_i,nxt_j);
  }
}

while(q.size()){
  I=q.front().F;
  J=q.front().S;
  q.pop();
  for(int i=0;i<4;i++){
    // next position
    I__=I+pos[i][0], J__=J+pos[i][1];
    if(!inRange(I__,J__)||vis[I__][J__]){
    	continue;
    }
    vis[I__][J__]=true;
    Graph[I__][J__]=Graph[I][J]+1;
    // count steps
    q.push({I__,J__});
  }
}

while(q.size()){
  I=q.front().F;
  J=q.front().S;
  q.pop();
  for(int i=0;i<4;i++){
    // next position
    I__=I+pos[i][0], J__=J+pos[i][1];
    if(!inRange(I__,J__)||vis[I__][J__]){
    	continue;
    }
    vis[I__][J__]=true;
    Graph[I__][J__]=Graph[I][J]+1;
    // count steps
    q.push({I__,J__});
  }
}

#define F first
#define S second
typedef pair<int,int> pii;

queue<pii> q;
q.push( {R,C} );

while( q.size() ){ // not empty
	BFS ...

}

int G[N][N];

int u ,v ;
while(m--){
// undirected
    cin>>u>>v;
    G[u][v]=1 ;
    G[v][u]=1 ;
}

int G[N][N];

int u ,v , wt;
while(m--){
// undirected
    cin>>u>>v>>wt;
    G[u][v]=wt ;
    // G[v][u]=wt ; directed
}

vector<int> Graph[N];

inline void Add_vertex_undirected(int a,int b){
    // Undirected graph
    Graph[a].push_back(b);
    Graph[b].push_back(a);
}

vector<pair<int,int> > Graph[N];

void Add_vertex_ditected(int v,int u,int e){
    //    edge
    // v---------> u
    // vertex v to u with edge= e
    Graph[v].push_back({u,e});
}

const int MAX_N = 1e5+5;

vector<int> G1[MAX_N];

vector<vector<int> > G2(MAX_N);