Modern art

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

#define I_2D(row, col, width) ((row) * (width) + (col))
#define PRINT_ARR(arr, n)                                                      \
  do {                                                                         \
    for (int i = 0; i < n; i++) {                                              \
      cout << arr[i] << " ";                                                   \
    }                                                                          \
    cout << "\n";                                                              \
  } while (0)
#define PRINT_VEC_ARR(v, n)                                                    \
  do {                                                                         \
    for (int i = 0; i < n; i++) {                                              \
      cout << i << ": ";                                                       \
      for (auto item : v[i]) {                                                 \
        cout << item << " ";                                                   \
      }                                                                        \
      cout << endl;                                                            \
    }                                                                          \
  } while (0)
#define endl '\n';

typedef long long ll;

int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int a, p;
  cin >> a >> p;
  ll opt_b = ceil(p / 4), opt_a = floor(p / 4);

  if (p & 1 || opt_a >= a || opt_a * opt_b < a) {
    cout << "IMPOSSIBLE" << endl;
    return 0;
  }

  cout << "POSSIBLE" << endl;
  ll count = a - (opt_a + opt_b - 1);
  for (int i = 0; i < opt_a + 2; i++) {
    for (int j = 0; j < opt_b + 2; j++) {
      if (i == 0 || i == opt_a + 2 - 1) {
        cout << "0";
        continue;
      }
      if (j == 0 || j == opt_b + 2 - 1) {
        cout << "0";
        continue;
      }
      if (i == 1) {
        cout << "1";
        continue;
      }
      if (j == 1) {
        cout << "1";
        continue;
      }
      if (count) {
        cout << "1";
        count--;
      } else {
        cout << "0";
      }
    }
    cout << endl;
  }

  return 0;
}

Test 1

Verdict: WRONG ANSWER

Test 2

Verdict: WRONG ANSWER

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: WRONG ANSWER

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: WRONG ANSWER

Test 11

Verdict: ACCEPTED

Test 12

Verdict: WRONG ANSWER

Test 13

Verdict: WRONG ANSWER

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: WRONG ANSWER

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: WRONG ANSWER

Test 23

Verdict: WRONG ANSWER

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: ACCEPTED

Test 27

Verdict: WRONG ANSWER

Test 28

Verdict: ACCEPTED

Test 29

Verdict: ACCEPTED

Test 30

Verdict: WRONG ANSWER

Test 31

Verdict: WRONG ANSWER

Test 32

Verdict: WRONG ANSWER

Test 33

Verdict: ACCEPTED

Test 34

Verdict: ACCEPTED

Test 35

Verdict: ACCEPTED

Test 36

Verdict: WRONG ANSWER

Test 37

Verdict: ACCEPTED

Test 38

Verdict: WRONG ANSWER

Test 39

Verdict: ACCEPTED

Test 40

Verdict: WRONG ANSWER

Test 41

Verdict: ACCEPTED

Test 42

Verdict: WRONG ANSWER

Test 43

Verdict: ACCEPTED

Test 44

Verdict: WRONG ANSWER

Test 45

Verdict: ACCEPTED

Test 46

Verdict: ACCEPTED

Test 47

Verdict: ACCEPTED

Test 48

Verdict: ACCEPTED

Test 49

Verdict: ACCEPTED

Test 50

Verdict: WRONG ANSWER