#include<cstdio>
#include<vector>
#include<queue>
using namespace std;

int used[1000],n,m,start,curLevel;
vector<int>gr[1000],level[1000];

void init(){
    int from,to;

    scanf("%d %d %d",&n,&m,&start);

    for(int i=0;i<m;i++){
        scanf("%d %d",&from,&to);

        gr[from].push_back(to);
        gr[to].push_back(from);
    }
}

void bfs(){
    queue<int>toVisit;
    int node,nodesOnLevel=1,nextNode;

    toVisit.push(start);
    level[0].push_back(start);
    used[start]=1;

    while(!toVisit.empty()){
        node=toVisit.front();
        toVisit.pop();
        nodesOnLevel--;

        for(int i=0;i<gr[node].size();i++){
            nextNode=gr[node][i];

            if(used[nextNode]==1)continue;

            level[curLevel+1].push_back(nextNode);
            toVisit.push(nextNode);
            used[nextNode]=1;
        }

        if(nodesOnLevel==0){
            curLevel++;
            nodesOnLevel=toVisit.size();
        }
    }
}

void print(){
    for(int i=0;level[i].size()!=0;i++){
        printf("nodes on level %d:",i);

        for(int j=0;j<level[i].size();j++){
            printf(" %d",level[i][j]);
        }

        printf("\n");
    }
}

int main(){
    init();
    bfs();
    print();
}