#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int MOD = 1000000007;
const int MOD2 = 998244353;
const ll INF = 1e18;
const int MX = 1000001; //check the limits, dummy
ll modExp(ll base, ll power) {
if (power == 0) {
return 1;
} else {
ll cur = modExp(base, power / 2); cur = cur * cur; cur = cur % MOD;
if (power % 2 == 1) cur = cur * base;
cur = cur % MOD;
return cur;
}
}
ll inv(ll base) {
return modExp(base, MOD-2);
}
ll mul(ll A, ll B) {
return (A*B)%MOD;
}
ll add(ll A, ll B) {
return (A+B)%MOD;
}
ll dvd(ll A, ll B) {
return mul(A, inv(B));
}
ll sub(ll A, ll B) {
return (A-B+MOD)%MOD;
}
ll cielDiv(ll A , ll B) {
return (A + B - 1)/B;
}
ll* facs = new ll[MX];
ll* facInvs = new ll[MX];
ll choose(ll a, ll b) {
if (b > a) return 0;
if (a < 0) return 0;
if (b < 0) return 0;
ll cur = facs[a];
cur = mul(cur, facInvs[b]);
cur = mul(cur, facInvs[a-b]);
return cur;
}
void initFacs() {
facs[0] = 1;
facInvs[0] = 1;
for (int i = 1 ; i < MX ; i ++ ) {
facs[i] = (facs[i-1] * i) % MOD;
facInvs[i] = inv(facs[i]);
}
}
ll n, m,k ;
const int maxn = 200005;
vector<ll> adj[maxn];
bool seen[maxn];
vector<ll> eulers;
void dfs(ll a, ll p) {
seen[a] = true;
eulers.push_back(a);
for (ll c : adj[a]) {
if (!seen[c]) {
dfs(c,a);
}
}
eulers.push_back(a);
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> n >> m >> k ;
for (int i = 0 ;i < m ; i ++) {
ll a , b; cin >> a >> b;
adj[a].push_back(b);
adj[b].push_back(a);
}
dfs(1,0);
// 1) correct ceiling
ll limit = ( (ll)eulers.size() + k - 1 ) / k;
// 2) print exactly k lines
int printed = 0, p = 0;
while (printed < k) {
if (p < (int)eulers.size()) {
int sz = min<ll>(limit, eulers.size() - p);
cout << sz;
for (int i = 0; i < sz; i++, p++) {
cout << ' ' << eulers[p];
}
cout << "\n";
} else {
// pad with a trivial single‐node tour
cout << "1 1\n";
}
printed++;
}
return 0;
}
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