#include <bits/stdc++.h>
using namespace std;
const long long int MOD = 0ll;
const long long int INF = 3e18;
long long int power(long long int base, long long int exp) {
  long long int res = 1;
  while (exp > 0) {
    if (exp % 2 == 1) res = (res * base);
    base = (base * base);
    exp /= 2;
  }
  return res;
}
long long int bitc(long long int n, long long int x) { return ((n >> x) & 1); }
long long int __gcd(long long int a, long long int b) {
  return b == 0 ? a : __gcd(b, a % b);
}
long long int fsub(long long int a, long long int b, long long int p = MOD) {
  return ((a % p) - (b % p) + p) % p;
}
long long int fmult(long long int a, long long int b, long long int p = MOD) {
  return ((((a % p) * (b % p)) % p) + p) % p;
}
long long int fadd(long long int a, long long int b, long long int p = MOD) {
  return ((a % p + b % p) % p + p) % p;
}
long long int fpow(long long int n, long long int k, long long int p = MOD) {
  long long int r = 1;
  while (k > 0) {
    if (k & 1) r = r * n % p;
    n = n * n % p;
    k = k >> 1;
  }
  return r;
}
long long int inv(long long int a, long long int p = MOD) {
  return fpow(a, p - 2, p);
}
long long int fdiv(long long int a, long long int b, long long int p = MOD) {
  long long int yinv = inv(b);
  long long int ans = (a * yinv) % p;
  return ((ans) % p + p) % p;
}
long long int ceil(long long int a, long long int b) {
  return ceil((long double)a / b);
}
template <typename T>
istream &operator>>(istream &in, vector<T> &a) {
  for (auto &item : a) {
    in >> item;
  }
  return in;
}
template <typename T, typename U>
ostream &operator<<(ostream &out, pair<T, U> &a) {
  cout << a.first << " " << a.second;
  return out;
}
template <typename T, typename U>
istream &operator>>(istream &out, pair<T, U> &a) {
  cin >> a.first >> a.second;
  return out;
}
template <typename T, typename U>
ostream &operator<<(ostream &out, map<T, U> &a) {
  for (auto &item : a) {
    out << item << "\n";
  }
  return out;
}
template <typename T>
ostream &operator<<(ostream &out, vector<T> &a) {
  for (auto &item : a) {
    out << item << " ";
  }
  return out;
}
template <typename T>
ostream &operator<<(ostream &out, vector<vector<T>> &a) {
  for (auto &item : a) {
    out << item << "\n";
  }
  return out;
}
template <int D, typename T>
struct Vec : public vector<Vec<D - 1, T>> {
  static_assert(D >= 1, "Vector dimension must be greater than zero!");
  template <typename... Args>
  Vec(int n = 0, Args... args)
      : vector<Vec<D - 1, T>>(n, Vec<D - 1, T>(args...)) {}
};
template <typename T>
struct Vec<1, T> : public vector<T> {
  Vec(int n = 0, T val = T()) : vector<T>(n, val) {}
};
std::vector<bool> is_prime;
std::vector<long long int> primes;
void sieve(long long int n) {
  is_prime.resize(n + 2, true);
  primes.clear();
  long long int p;
  for (p = 2; p * p <= n; p++) {
    if (is_prime[p]) {
      long long int i;
      for (i = p * p; i <= n; i += p) {
        is_prime[i] = false;
      }
    }
  }
  is_prime[0] = is_prime[1] = false;
  long long int i;
  for (i = 2; i <= n; i++) {
    if (is_prime[i]) {
      primes.emplace_back(i);
    }
  }
}
map<long long int, long long int> prime_factors(long long int n) {
  map<long long int, long long int> s;
  long long int i;
  long long int tc = 0;
  while (n % 2 == 0) {
    tc++;
    n /= 2;
  }
  if (tc > 0) {
    s[2] = tc;
  }
  for (i = 3; i <= sqrt(n); i += 2) {
    tc = 0;
    while (n % i == 0) {
      tc++;
      n /= i;
    }
    if (tc > 0) {
      s[i] = tc;
    }
  }
  if (n > 2) {
    s[n] += 1;
  }
  return s;
}
std::vector<long long int> fact_vec;
void fact_fun(long long int n) {
  fact_vec.resize(n + 10);
  long long int i;
  fact_vec[0] = 1;
  for (i = 1; i <= n + 2; i++) {
    fact_vec[i] = (fact_vec[i - 1] * i) % MOD;
  }
}
std::vector<long long int> p2;
void power_2(long long int n, long long int m = MOD) {
  long long int i;
  p2.emplace_back(1);
  for (i = 0; i < n; i++) {
    p2.emplace_back(fmult(p2.back(), 2));
  }
}
long long int ncr(long long int n, long long int r) {
  if (r > n) return 0;
  return fdiv(fact_vec[n], fmult(fact_vec[r], fact_vec[n - r]));
}
std::vector<long long int> spf;
void sieve2(long long int MAXN) {
  MAXN += 10;
  spf.resize(MAXN, 0);
  spf[1] = 1;
  for (long long int i = 2; i < MAXN; i++) spf[i] = i;
  for (long long int i = 4; i < MAXN; i += 2) spf[i] = 2;
  for (long long int i = 3; i * i < MAXN; i++) {
    if (spf[i] == i) {
      for (long long int j = i * i; j < MAXN; j += i) {
        if (spf[j] == j) spf[j] = i;
      }
    }
  }
}
const int mi[4] = {-1, 0, 1, 0}, mj[4] = {0, 1, 0, -1};
const int d8i[8] = {-1, -1, 0, 1, 1, 1, 0, -1},
          d8j[8] = {0, 1, 1, 1, 0, -1, -1, -1};
map<long long int, long long int> getFactorization(long long int x) {
  map<long long int, long long int> ret;
  while (x != 1) {
    ret[spf[x]]++;
    x = x / spf[x];
  }
  return ret;
}
class Sol {
 public:
  Sol() { long long int i, j; }
};
string solve() {
  long long int i, j;
  long long int a, b, c, d;
  cin >> a >> b >> c >> d;
  long long int z = 0, o = 0;
  bool cool = true;
  auto f = [&](long long int a) {
    long long int z = 0;
    while (z * (z - 1) < 2 * a) {
      z++;
    }
    if (z * (z - 1) != 2 * a) {
      cool = false;
    }
    if (z == 0 && (b || c)) {
      z++;
    }
    return z;
  };
  z = f(a);
  o = f(d);
  if (!cool) {
    return "Impossible";
  }
  string ans = string(z, '0') + string(o, '1');
  long long int cur = z * o;
  long long int have = o;
  long long int sc = 0;
  while (z * have > b && have) {
    if (z * (have - 1) < b) {
      break;
    }
    ans.pop_back();
    sc++;
    have--;
  }
  if (sc != 0) {
    ans = string(sc, '1') + ans;
  }
  long long int n = ans.length();
  long long int sh = 0;
  while ((z - sh) * have + sh * (have - 1) > b && have) {
    sh++;
  }
  if (sh && !have) {
    return "Impossible";
  }
  if (sh) {
    for (i = n - 1; i >= 0; i--) {
      if (ans[i] == '0') {
        break;
      }
    }
    i++;
    ans.erase(ans.begin() + i);
    ans.insert(ans.begin() + i - sh, '1');
  }
  long long int zo = 0, oz = 0;
  long long int ox = 0, zx = 0;
  for (i = n - 1; i >= 0; i--) {
    if (ans[i] == '1') {
      ox++;
    } else {
      zo += ox;
    }
  }
  for (i = n - 1; i >= 0; i--) {
    if (ans[i] == '0') {
      zx++;
    } else {
      oz += zx;
    }
  }
  if (zo != b || oz != c) {
    return "Impossible";
  }
  if (ans.empty()) {
    ans = "0";
  }
  return ans;
}
int main() {
  long long int i, j;
  ios::sync_with_stdio(false);
  cin.tie(0);
  long long int ti;
  ti = 1;
  while (ti--) {
    cout << solve() << "\n";
  }
  return 0;
}
