#include <bits/stdc++.h>
using namespace std;
string s;
int a00, a01, a10, a11, n, m, cnt1, cnt0;
int bfzero = 0;
int f(long long x) {
  int d = sqrt(8 * x + 1);
  int n0 = (-1 + d) / 2;
  return n0;
}
void build(int a00, int a01, int a10, int a11) {
  n = f(a00) + 1;
  m = f(a11) + 1;
  if (n * (n - 1) / 2 != a00 || (m * (m - 1) / 2 != a11)) {
    cout << "Impossible";
    return;
  }
  if (a01 == 0 and a10 == 0) {
    if (a00 == 0) {
      for (int i = 0; i < m; i++) {
        cout << '1';
      }
      cout << endl;
      return;
    } else if (a11 == 0) {
      for (int i = 0; i < n; i++) {
        cout << '0';
      }
      cout << endl;
      return;
    }
  }
  if (n * m != (a01 + a10)) {
    cout << "Impossible";
    return;
  }
  int cnt1 = m, cnt0 = n;
  for (int i = 0; i <= cnt0; i++) {
    while (a10 >= cnt0 - i && a01 >= i) {
      cout << 1;
      a10 -= cnt0 - i;
      a01 -= i;
    }
    if (i != cnt0) {
      cout << 0;
    }
  }
}
int main() {
  cin >> a00 >> a01 >> a10 >> a11;
  build(a00, a01, a10, a11);
  return 0;
}
