Modern art

#include <bits/stdc++.h>
using namespace std;
#define rep(i, a, b) for(int i=a;i<(b);++i)
#define all(x) begin(x),end(x)
#define sz(x) int((x).size())
using ll = long long;
using pii = pair<int,int>;
using vi = vector<int>;
using ld = long double;

int a, p, sl;
int cx = 2, cy = 2;
bool Z[1002][1001];
bool balance = false;

int main() {
  cin >> a >> p;
  if (p > 2*a+2) {
    cout << "IMPOSSIBLE\n";
    return 0;
  }
  sl = int(sqrt(a));
  a -= sl*2-1;
  p -= sl*4;
  rep(i,0,sl) {
    Z[0][i] = 1;
    Z[i][0] = 1;
  }
  if (sl*sl < a) {
    a -= 1;
    p -= 2;
    Z[0][sl] = 1;
    if ((sl+1)*sl < a) {
      a -= 1;
      p -= 2;
      Z[sl][0] = 1;
    }
    ++sl;
  }
  if (p < 0) {
    cout << "IMPOSSIBLE\n";
    return 0;
  }
  assert(a >= 0);
  while (a > 0) {
    if (p < a*2) {
      cout << "IMPOSSIBLE\n";
      return 0;
    }
    if (p > a*2) {
      Z[cy][cx] = 1;
      p -= 3;
      ++cx;
      if (cx == sl) {
        cx = 1;
        ++cy;
      }
    }
    if (p == a*2) {
      cx = sl;
      while (a > 0) {
        Z[0][cx++] = 1;
        ++sl;
        --a;
      }
    }
    a -= 1;
  }
  cout << "POSSIBLE\n";
  rep(i,0,sl) cout << "0";
  cout << "00\n";
  rep(i,0,sl+1) {
    cout << "0";
    rep(j,0,sl) {
      cout << Z[i][j];
    }
    cout << "0\n";
  }
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

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: ACCEPTED

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: WRONG ANSWER

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED

Test 23

Verdict: WRONG ANSWER

Test 24

Verdict: ACCEPTED

Test 25

Verdict: ACCEPTED

Test 26

Verdict: WRONG ANSWER

Test 27

Verdict: ACCEPTED

Test 28

Verdict: WRONG ANSWER

Test 29

Verdict: ACCEPTED

Test 30

Verdict: WRONG ANSWER

Test 31

Verdict: ACCEPTED

Test 32

Verdict: ACCEPTED

Test 33

Verdict: WRONG ANSWER

Test 34

Verdict: WRONG ANSWER

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: WRONG ANSWER

Test 44

Verdict: WRONG ANSWER

Test 45

Verdict: ACCEPTED

Test 46

Verdict: WRONG ANSWER

Test 47

Verdict: ACCEPTED

Test 48

Verdict: WRONG ANSWER

Test 49

Verdict: ACCEPTED

Test 50

Verdict: WRONG ANSWER