#include <bits/stdc++.h>
using namespace std;
long long a[4], num1, num0;
int main() {
  cin >> a[0] >> a[1] >> a[2] >> a[3];
  if (a[0] == 0 && a[1] == 0 && a[2] == 0 && a[3] == 0) {
    puts("0");
    return 0;
  }
  long long tmp = sqrt(1 + 8 * a[0]);
  if (tmp * tmp != 1 + 8 * a[0] || (1 + tmp) & 1) {
    puts("Impossible");
    return 0;
  }
  num0 = (1 + tmp) >> 1;
  tmp = sqrt(1 + 8 * a[3]);
  if (tmp * tmp != 1 + 8 * a[3] || (1 + tmp) & 1) {
    puts("Impossible");
    return 0;
  }
  num1 = (1 + tmp) >> 1;
  if (a[0] == 0 && a[1] == 0 && a[2] == 0) {
    for (int i = 1; i <= num1; i++) printf("1");
    puts("");
    return 0;
  }
  if (a[1] == 0 && a[2] == 0 && a[3] == 0) {
    for (int i = 1; i <= num0; i++) printf("0");
    puts("");
    return 0;
  }
  if ((long long)num0 * num1 != a[1] + a[2]) {
    puts("Impossible");
    return 0;
  }
  if (num0 == 0) {
    for (int i = 1; i <= num1; i++) printf("1");
    puts("");
    return 0;
  }
  if (num1 == 0) {
    for (int i = 1; i <= num0; i++) printf("0");
    puts("");
    return 0;
  }
  int sum = a[1] / num1, left = a[1] % num1;
  for (int i = 1; i <= sum; i++) printf("0");
  for (int i = 1; i <= num1 - left; i++) printf("1");
  if (num0 - sum) printf("0");
  for (int i = 1; i <= left; i++) printf("1");
  for (int i = sum + 2; i <= num0; i++) printf("0");
  puts("");
  return 0;
}
