#include<bits/stdc++.h> using namespace std; vector<vector<int> >v(100005); int main() { int n,m,x,y; cin>>n>>m; for(int i=1;i<=m;i++) { cin>>x>>y; v[x-1].push_back(y); } for(int i=0;i<n;i++) { if(v[i].size()!=0) { cout<<v[i].size()<<" "; sort(v[i].begin(),v[i].end()); for(int j=0;j<v[i].size();j++) { cout<<v[i][j]<<" "; } cout<<endl; }

}
return 0;

}