#include <bits/stdc++.h>
using namespace std;
const int maxn = 200000 + 10;
int a, b, c, d, ans[maxn];
int main() {
  cin >> a >> b >> c >> d;
  if (a == 0 && b == 0 && c == 0 && d == 0) {
    puts("0");
    return 0;
  }
  int x = -1, y = -1;
  for (int i = 1; i <= 100000; i++)
    if ((long long)i * (i - 1) / 2 == a) x = i;
  for (int i = 1; i <= 100000; i++)
    if ((long long)i * (i - 1) / 2 == d) y = i;
  if (x == 1 && b == 0 && c == 0) x = 0;
  if (y == 1 && b == 0 && c == 0) y = 0;
  if (x == -1 || y == -1) {
    puts("Impossible");
    return 0;
  }
  int zero = 0, one = 0, sum0 = 0, sum1 = 0;
  for (int i = 1; i <= x + y; i++) {
    if (sum0 + (y - one) <= b && zero <= x) {
      sum0 += y - one;
      zero++;
      ans[i] = 0;
    } else {
      if (sum1 + (x - zero) > c || one >= y) {
        puts("Impossible");
        return 0;
      }
      sum1 += x - zero;
      one++;
      ans[i] = 1;
    }
  }
  if (sum0 != b || sum1 != c) {
    puts("Impossible");
    return 0;
  }
  for (int i = 1; i <= x + y; i++) printf("%d", ans[i]);
  return 0;
}
