#include <bits/stdc++.h>
using namespace std;
const int maxn = 100005;
const double pi = acos(-1.0);
const double e = 2.71828182845904523536;
int C2(int x) {
  long long tmp = x * (x - 1) / 2;
  return (int)tmp;
}
int main() {
  int a, b, c, d;
  scanf("%d%d%d%d", &a, &b, &c, &d);
  int flag = 0;
  int A = 0, B = 0;
  for (int i = 0; C2(i) <= a; i++) {
    if (C2(i) == a) {
      for (int j = 0; C2(j) <= d; j++) {
        if (C2(j) == d) {
          if (i * j == b + c) {
            A = i;
            B = j;
            flag = 1;
          }
        }
      }
    }
  }
  if (!flag)
    printf("Impossible\n");
  else {
    int sum = A + B;
    for (int i = 1; i <= sum; i++) {
      if (c >= A) {
        c -= A;
        B--;
        printf("1");
      } else {
        A--;
        printf("0");
      }
    }
    printf("\n");
  }
  return 0;
}
