#include <bits/stdc++.h>
std::mt19937 rd(std::chrono::steady_clock::now().time_since_epoch().count());
using namespace std;
namespace io {
template <typename T>
inline void read(T& a) {
  int c = getchar(), sign = 0;
  a = 0;
  while (c < '0' || c > '9') sign += (c == '-'), c = getchar();
  while (c >= '0' && c <= '9') a = (a << 1) + (a << 3) + c - 48, c = getchar();
  if (sign & 1) a = -a;
}
template <typename T, typename... _T>
inline void read(T& a, _T&... argc) {
  read(a);
  read(argc...);
}
template <typename T>
inline void Write(T a) {
  if (a > 9) Write(a / 10);
  putchar(a % 10 + '0');
}
template <typename T>
inline void write(T a, char ch = ' ') {
  if (a < 0) putchar('-'), a = -a;
  Write(a);
  putchar(ch);
}
template <typename T>
inline void Min(T& a, T b) {
  a = min(a, b);
}
template <typename T>
inline void Max(T& a, T b) {
  a = max(a, b);
}
}  // namespace io
using namespace io;
const int maxn = 1e5;
const int N = 4e5 + 3;
const int mod = 998244353;
int n, m, q;
int dem[N], id[N], chot[N], a[N];
int k, h;
long long t[maxn + 2], dp[N + 3];
string second;
bool kt[N];
map<int, int> maps;
vector<pair<int, int>> edge[N];
map<int, int>::iterator it;
template <typename T>
void answer(T x) {
  cout << x;
  exit(0);
}
void putstring(string x, char ch = ' ') {
  for (char c : x) putchar(c);
  putchar(ch);
}
int main() {
  ios_base::sync_with_stdio(false), cin.tie(NULL);
  cin >> q;
  while (q--) {
    cin >> n >> m;
    vector<pair<int, int>> in;
    for (int i = 1; i <= m; ++i) {
      int u, v;
      cin >> u >> v;
      in.emplace_back(make_pair(u, v));
    }
    vector<int> res;
    for (int i = 0; i < m; ++i) {
      pair<int, int> x = in[i];
      if (!kt[x.first] && !kt[x.second]) {
        kt[x.first] = kt[x.second] = true;
        res.emplace_back(i + 1);
      }
    }
    if (res.size() >= n) {
      cout << "Matching\n";
      for (int i = 0; i < n; ++i) cout << res[i] << ' ';
      cout << "\n";
    } else {
      res.clear();
      for (int i = 1; i <= 3 * n; ++i)
        if (!kt[i]) res.push_back(i);
      cout << "IndSet\n";
      for (int i = 0; i < n; ++i) cout << res[i] << " ";
      cout << "\n";
    }
    for (int i = 1; i <= 3 * n; ++i) kt[i] = false;
  }
}
