#include <bits/stdc++.h>
using namespace std;
int main() {
  long long a00, a01, a10, a11;
  scanf("%I64d %I64d %I64d %I64d", &a00, &a01, &a10, &a11);
  if (a00 == 0 && a01 == 0 && a10 == 0 && a11 == 0) {
    printf("1");
    return 0;
  }
  long long c0 = 0;
  while (c0 * (c0 - 1) / 2 < a00) c0++;
  if (c0 * (c0 - 1) / 2 != a00) {
    printf("Impossible\n");
    return 0;
  }
  long long c1 = 0;
  while (c1 * (c1 - 1) / 2 < a11) c1++;
  if (c1 * (c1 - 1) / 2 != a11) {
    printf("Impossible\n");
    return 0;
  }
  if (a10 + a01 > 0) {
    if (c0 == 0) c0 = 1;
    if (c1 == 0) c1 = 1;
  }
  if (c0 * c1 != a10 + a01) {
    printf("Impossible\n");
    return 0;
  }
  if (c0 == 0) {
    for (int i = 0; i < c1; i++) printf("1");
    return 0;
  }
  if (c1 == 0) {
    for (int i = 0; i < c0; i++) printf("0");
    return 0;
  }
  for (int i = 0; i < a01 / c1; i++) printf("0");
  if (a01 % c1 == 0) {
    for (int i = 0; i < c1; i++) printf("1");
    for (int i = 0; i < c0 - a01 / c1; i++) printf("0");
  } else {
    for (int i = 0; i < c1 - a01 % c1; i++) printf("1");
    printf("0");
    for (int i = 0; i < a01 % c1; i++) printf("1");
    for (int i = 0; i < c0 - a01 / c1 - 1; i++) printf("0");
  }
  return 0;
}
