#include <bits/stdc++.h>
using namespace std;
int mysqrt(long long x) {
  int l = 0, r = 1e9 + 1;
  while (r - l > 1) {
    int m = (l + r) / 2;
    if (m * (long long)m <= x)
      l = m;
    else
      r = m;
  }
  return l;
}
mt19937 rnd(1337);
long long AR = 19, BR = 13, CR = 23, XR = 228, YR = 322, MODR = 1e9 + 993;
long long myrand() {
  long long ZR = (XR * AR + YR * BR + CR) % MODR;
  XR = YR;
  YR = ZR;
  return ZR;
}
const int Mod = 1e9 + 7;
int bpow(int x, int y) {
  if (y == 0) return 1;
  if (y == 1) return x;
  int ret = bpow(x, y >> 1);
  ret = (ret * (long long)ret) % Mod;
  if (y & 1) ret = (ret * (long long)x) % Mod;
  return ret;
}
int bdiv(int x, int y) { return (x * (long long)bpow(y, Mod - 2)) % Mod; }
void setmin(int &x, int y) { x = min(x, y); }
void setmax(int &x, int y) { x = max(x, y); }
void setmin(long long &x, long long y) { x = min(x, y); }
void setmax(long long &x, long long y) { x = max(x, y); }
int gcd(int a, int b) { return a ? gcd(b % a, a) : b; }
const long long llinf = 2e18 + 100;
const double eps = 1e-9;
const int maxn = 2e5 + 100, maxw = 1e6 + 100, inf = 2e9 + 100, sq = 300,
          mod = 1e9 + 7, LG = 17;
int n;
vector<int> e[maxn];
int p[maxn];
int get(int x) { return x == p[x] ? x : p[x] = get(p[x]); }
bool uni(int x, int y) {
  x = get(x);
  y = get(y);
  if (x == y) return 0;
  p[x] = y;
  return 1;
}
int eu[2 * maxn];
int sz;
void dfs(int v, int par) {
  eu[sz++] = v;
  for (auto i : e[v])
    if (i != par) dfs(i, v), eu[sz++] = v;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, m, k;
  cin >> n >> m >> k;
  for (int i = 0; i < n; i++) p[i] = i;
  for (int i = 0; i < m; i++) {
    int v, u;
    cin >> v >> u;
    v--;
    u--;
    if (uni(v, u)) e[v].push_back(u), e[u].push_back(v);
  }
  dfs(0, -1);
  int w = (2 * n + k - 1) / k;
  int now = 0;
  for (int i = 0; i < k; i++) {
    cout << max(1, min(w, sz - now));
    if (now == sz) {
      cout << ' ' << 1 << '\n';
      continue;
    }
    for (int j = 0; j < min(sz - now, w); j++) cout << ' ' << eu[now + j] + 1;
    cout << '\n';
    now += min(sz - now, w);
  }
}
