#include <bits/stdc++.h>
using namespace std;
long long calc(long long n) {
  long long i = 1;
  while (i * (i - 1) / 2 < n) {
    i++;
  }
  if (i * (i - 1) / 2 == n) {
    return i;
  }
  return -1;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  long long a00, a01, a10, a11;
  cin >> a00 >> a01 >> a10 >> a11;
  long long n = calc(a00 + a01 + a10 + a11);
  if (a00 + a01 + a10 + a11 == 0) {
    cout << "0\n";
  } else if (n == -1) {
    cout << "Impossible\n";
  } else if (a00 == 0 && a01 == 0 && a10 == 0) {
    cout << string(n, '1') << '\n';
  } else if (a11 == 0 && a01 == 0 && a10 == 0) {
    cout << string(n, '0') << '\n';
  } else {
    long long n0 = calc(a00);
    long long n1 = calc(a11);
    if (n0 == -1 || n1 == -1 || n0 + n1 != n) {
      cout << "Impossible\n";
    } else if (a10 == 0) {
      cout << string(n0, '0') + string(n1, '1') << '\n';
    } else {
      cout << string(n0 - (a10 + n1 - 1) / n1, '0') +
                  string(a10 % n1 == 0 ? n1 : a10 % n1, '1') + "0" +
                  string(n1 - (a10 % n1 == 0 ? n1 : a10 % n1), '1') +
                  string((a10 + n1 - 1) / n1 - 1, '0')
           << '\n';
    }
  }
  return 0;
}
