#include <bits/stdc++.h>
using namespace std;
using ll = long long;
ll f(ll x) { return x * (x - 1) / 2; }
ll a, b, c, d;
int main() {
  cin >> a >> b >> c >> d;
  ll n, m;
  for (ll i = 0; f(i) <= a; ++i)
    if (f(i) == a)
      for (ll j = 0; f(j) <= d; ++j)
        if (f(j) == d)
          if (i * j == b + c) {
            n = i;
            m = j;
            goto next;
          }
  puts("Impossible");
  return 0;
next:;
  if (n == 0 && m == 0) {
    puts("0");
    return 0;
  }
  ll s = n + m;
  for (ll i = 0; i < s; ++i) {
    if (c >= n) {
      --m;
      c -= n;
      printf("1");
    } else {
      --n;
      printf("0");
    }
  }
  puts("");
  return 0;
}
