#include <fstream>
#include <vector>
#include <stack>
#include <iostream>
using namespace std;

ifstream fin("inaltime.in");
ofstream fout("inaltime.out");
int dp[100005][17];
vector<int> L[100005];
int main()
{
    int n, m;
    fin >> n >> m;
    dp[1][0] = 1;
    for (int i = 2; i <= n; i++)
    {
        fin >> dp[i][0];
        L[dp[i][0]].push_back(i);
    }
    for (auto it : L)
    {
        for (auto ind : it)
            fout << ind << " ";
        fout << "\n";
    }
    return 0;
}