#include <bits/stdc++.h>
using namespace std;
template <class T>
void read(T& num) {
  char CH;
  bool F = false;
  for (CH = getchar(); CH < '0' || CH > '9'; F = CH == '-', CH = getchar())
    ;
  for (num = 0; CH >= '0' && CH <= '9';
       num = num * 10 + CH - '0', CH = getchar())
    ;
  F && (num = -num);
}
int stk[70], tp;
template <class T>
inline void print(T p) {
  if (!p) {
    puts("0");
    return;
  }
  while (p) stk[++tp] = p % 10, p /= 10;
  while (tp) putchar(stk[tp--] + '0');
  putchar('\n');
}
const long long mod = 1e9 + 7;
const double PI = acos(-1.0);
const int inf = 1e9;
const int N = 1e5 + 10;
const int maxn = 1e3 + 20;
const double eps = 1e-12;
int check(int x) {
  int l = 1, r = 1000005;
  if (x == 0) return 0;
  while (l <= r) {
    int mid = (l + r) >> 1;
    if ((long long)mid * (mid - 1) < (long long)2 * x)
      l = mid + 1;
    else
      r = mid - 1;
  }
  return l;
}
int main() {
  int a, b, c, d;
  read(a);
  read(b);
  read(c);
  read(d);
  int x = check(a), y = check(d);
  if (x == 0 && (b || c)) x = 1;
  if (y == 0 && (b || c)) y = 1;
  if ((long long)x * (x - 1) != (long long)2 * a ||
      (long long)y * (y - 1) != (long long)2 * d ||
      (long long)x * y != (long long)b + c)
    cout << "Impossible\n";
  else {
    if (x == 0 && y == 0)
      printf("0");
    else if (x == 0) {
      for (int i = 1; i <= y; i++) printf("1");
    } else if (y == 0) {
      for (int i = 1; i <= x; i++) printf("0");
    } else {
      int t = b / y, f = y - b % y;
      for (int i = 1; i <= t; i++) printf("0"), x--;
      for (int i = 1; i <= f; i++) printf("1"), y--;
      if (x > 0) {
        printf("0");
        x--;
      }
      for (int i = 1; i <= y; i++) printf("1");
      for (int i = 1; i <= x; i++) printf("0");
    }
  }
  return 0;
}
