#include <bits/stdc++.h>
using namespace std;
long long a, b, c, d;
map<long long, long long> vis;
void init() {
  long long now = 1;
  for (int i = 2; i <= 1000000; i++) {
    vis[now] = i;
    now += i;
    if (now > 1000000000) break;
  }
}
char s[1000005];
int main() {
  cin >> a >> b >> c >> d;
  init();
  if ((a && !vis[a]) || (d && !vis[d])) {
    printf("Impossible\n");
    return 0;
  }
  long long n0 = vis[a];
  long long n1 = vis[d];
  long long tot = n0 * n1;
  if (!n1 && !n0) {
    if (!b && !c)
      cout << '1' << endl;
    else if (b == 1 && c == 0)
      cout << "01" << endl;
    else if (b == 0 && c == 1)
      cout << "10" << endl;
    else
      cout << "Impossible" << endl;
    return 0;
  }
  if (n1 + n0 > 1000000) {
    printf("Impossible\n");
    return 0;
  }
  if (b == tot - c) {
    if (!n1) {
      for (int i = 0; i < n0; i++) cout << '0';
      cout << endl;
      return 0;
    }
    int e = b / n1, f = b % n1;
    for (int i = 0; i < e; i++) cout << '0';
    for (int i = 0; i < n1 - f; i++) cout << '1';
    if (e - f < n0) cout << '0';
    for (int i = 0; i < f; i++) cout << '1';
    for (int i = 0; i < n0 - 1 - e; i++) cout << '0';
    cout << endl;
  } else {
    if (!n1) n1 = 1;
    if (!n0) n0 = 1;
    tot = n0 * n1;
    if (b == tot - c) {
      int e = b / n1, f = b % n1;
      for (int i = 0; i < e; i++) cout << '0';
      for (int i = 0; i < n1 - f; i++) cout << '1';
      if (e - f < n0) cout << '0';
      for (int i = 0; i < f; i++) cout << '1';
      for (int i = 0; i < n0 - 1 - e; i++) cout << '0';
      cout << endl;
    } else {
      cout << "Impossible" << endl;
    }
  }
  return 0;
}
