#include <bits/stdc++.h>
using namespace std;
int main() {
  int i, j, k;
  long long a, b, c, d;
  scanf("%lld", &a);
  scanf("%lld", &b);
  scanf("%lld", &c);
  scanf("%lld", &d);
  long long x = (-1 + sqrt(1 + 8 * a)) / 2;
  long long y = (-1 + sqrt(1 + 8 * d)) / 2;
  if (a == 0 && b == 0 && c == 0 && d == 0) {
    printf("1\n");
    return 0;
  } else if (b == 0 && c == 0) {
    if (a == 0 && (y * (y + 1)) / 2 == d) {
      y++;
      while (y--) printf("1");
    } else if (d == 0 && (x * (x + 1)) / 2 == a) {
      x++;
      while (x--) printf("0");
    } else
      printf("Impossible\n");
    return 0;
  }
  x++;
  y++;
  if ((x * (x - 1)) / 2 != a || (y * (y - 1)) / 2 != d || x * y != b + c) {
    printf("Impossible\n");
    return 0;
  }
  long long p, q, r, s, t;
  p = b / y;
  if (b % y == 0)
    r = 0;
  else
    r = 1;
  s = b % y;
  t = x - p - r;
  q = y - s;
  while (p--) printf("0");
  while (q--) printf("1");
  while (r--) printf("0");
  while (s--) printf("1");
  while (t--) printf("0");
  return 0;
}
