#include <bits/stdc++.h>
using namespace std;
int n, a00, a01, a10, a11, x, y, z, now;
bool qwq;
int main() {
  scanf("%d%d%d%d", &a00, &a01, &a10, &a11);
  if (a00 == 0 && a11 == 0 && a01 == 0 && a10 == 0) return puts("0"), 0;
  a00 <<= 1, a11 <<= 1;
  if (a00 || a10 || a01)
    for (x = 1; x * (x - 1) < a00; x++)
      ;
  if (x * (x - 1) > a00) return puts("Impossible"), 0;
  if (a01 || a10 || a11)
    for (y = 1; y * (y - 1) < a11; y++)
      ;
  if (y * (y - 1) > a11) return puts("Impossible"), 0;
  if (x * y != a01 + a10) return puts("Impossible"), 0;
  while (x) {
    if (now + y > a10) break;
    z++, x--, now += y;
  }
  if (a10 - now) qwq = 1;
  for (int i = 0; i < x - qwq; i++) printf("0");
  for (int i = 0; i < a10 - now; i++) printf("1");
  if (qwq) printf("0");
  for (int i = a10 - now; i < y; i++) printf("1");
  for (int i = 0; i < z; i++) printf("0");
}
