#include <bits/stdc++.h>
using namespace std;
long long f(long long x) { return x * (x - 1) / 2; }
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout.tie(0);
  long long a, b, c, d;
  cin >> a >> b >> c >> d;
  long long n = -1, m = -1;
  for (long long i = 0; f(i) <= a; i++)
    if (f(i) == a) {
      for (long long j = 0; f(j) <= d; j++)
        if (f(j) == d) {
          if (i * j == b + c) {
            n = i, m = j;
            break;
          }
        }
      if (n != -1) break;
    }
  if (n == -1) {
    cout << "Impossible" << endl;
    return 0;
  }
  if (n == 0 && m == 0) {
    cout << 0 << endl;
    return 0;
  }
  long long s = n + m;
  for (long long i = 0; i < s; i++) {
    if (c >= n) {
      m--;
      c -= n;
      cout << 1;
    } else {
      n--;
      cout << 0;
    }
  }
  cout << endl;
  return 0;
}
