#include <bits/stdc++.h>
inline void inp(long long int &n) {
  n = 0;
  int ch = getchar();
  int sign = 1;
  while (ch < '0' || ch > '9') {
    if (ch == '-') sign = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9')
    n = (n << 3) + (n << 1) + ch - '0', ch = getchar();
  n = n * sign;
}
using namespace std;
int n, m;
int a, b, c, d;
bool f = true;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> a >> b >> c >> d;
  for (n = sqrt(2.0 * a); n * (n - 1) <= a * 2; n++) {
    if (n * (n - 1) == a * 2) {
      for (m = sqrt(2.0 * d); m * (m - 1) <= d * 2; m++) {
        if (m * (m - 1) == d * 2) {
          if (n * m == b + c) f = false;
        }
        if (!f) break;
      }
    }
    if (!f) break;
  }
  if (f)
    cout << "Impossible" << endl;
  else if (n == 0 && m == 0)
    cout << 1 << endl;
  else {
    for (; n + m;) {
      if (b >= m) {
        b -= m;
        n--;
        cout << 0;
      } else {
        cout << 1;
        m--;
      }
    }
    cout << endl;
  }
  return 0;
}
