#include <bits/stdc++.h>
using namespace std;
int main() {
  long long a, b, c, d;
  cin >> a >> b >> c >> d;
  if (abs(c - d) > 1) {
    cout << "-1";
    return 0;
  }
  if (max(c, d) > min(a, b)) {
    cout << "-1";
    return 0;
  }
  if (a + b <= c + d) {
    cout << "-1";
    return 0;
  }
  if (c == d) {
    a--;
    for (int i = 1; i <= a - c; i++) cout << '4';
    if (a == c - 1 && b > 1) {
      cout << '7';
      b--;
    }
    for (int i = 1; i <= c; i++) cout << "47";
    for (int i = 1; i <= b - c; i++) cout << '7';
    if (a - c >= 0) cout << '4';
  }
  if (c > d) {
    for (int i = 1; i <= a - c; i++) cout << '4';
    for (int i = 1; i <= c; i++) cout << "47";
    for (int i = 1; i <= b - c; i++) cout << '7';
  }
  if (c < d) {
    if (b > 1) {
      cout << '7';
      b--;
    }
    for (int i = 1; i < a - c; i++) cout << '4';
    for (int i = 1; i <= c; i++) cout << "47";
    for (int i = 1; i <= b - c; i++) cout << '7';
    cout << '4';
  }
}
