3SUM

input/code.cpp: In function 'int main()':
input/code.cpp:31:2: error: expected '}' at end of input
   31 | }
      |  ^
input/code.cpp:9:12: note: to match this '{'
    9 | int main() {
      |            ^

#include <bits/stdc++.h>
using namespace std;
using ll = long long;

const int N = 5000;
unordered_set<ll> S;
int T[N];

int main() {
  ll n, x;
  cin >> n >> x;
  for (int i = 0; i < n; ++i) {
    int k;
    cin >> k;
    T[i] = k;
    S.insert(i);
  }
  for (int i = 0; i < n; ++i) {
    S.erase(T[i]);
    for (int j = 0; j < i; ++j) {
      ll k = x - T[i] - T[j];
      if (S.count(k)) {
        int ind = i+1;
        while (T[ind] != k) ++ind;
        cout << i+1 << ' ' << j+1 << ' ' << ind+1 << '\n';
        return 0;
      }
    
  }
  cout << "IMPOSSIBLE\n";
}