#include <bits/stdc++.h>
using namespace std;
deque<int> dq;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int i, j, k, l, n, m, p, q, first = -1, la = -1;
  cin >> n >> m >> p >> q;
  int flag = 0;
  if (abs(p - q) > 1)
    flag = 1;
  else {
    if (p > q) {
      for (i = 0; i < p; i++) {
        dq.push_back(4);
        dq.push_back(7);
        n--;
        m--;
      }
      if (n < 0 || m < 0)
        flag = 1;
      else {
        int sz = dq.size();
        for (i = 0; i < sz; i++) {
          if (dq[i] == 4 && first == -1)
            first = i;
          else if (dq[i] == 7)
            la = i;
        }
        for (i = 0; i < sz; i++) {
          cout << dq[i];
          if (i == first) {
            while (n--) cout << '4';
          }
          if (i == la) {
            while (m--) cout << '7';
          }
        }
      }
    } else if (q > p) {
      for (i = 0; i < q; i++) {
        dq.push_back(7);
        dq.push_back(4);
        n--;
        m--;
      }
      if (n < 0 || m < 0)
        flag = 1;
      else {
        int sz = dq.size();
        for (i = 0; i < sz; i++) {
          if (dq[i] == 4 && first == -1)
            first = i;
          else if (dq[i] == 7)
            la = i;
        }
        for (i = 0; i < sz; i++) {
          cout << dq[i];
          if (i == first) {
            while (n--) cout << '4';
          }
          if (i == la) {
            while (m--) cout << '7';
          }
        }
      }
    } else {
      if (p == 1) {
        if (n > 1) {
          dq.push_back(4);
          dq.push_back(7);
          dq.push_back(4);
          n -= 2;
          m--;
        } else {
          dq.push_back(7);
          dq.push_back(4);
          dq.push_back(7);
          n -= 1;
          m -= 2;
        }
      } else {
        if (n >= p + 1) {
          for (i = 0; i < p; i++) {
            dq.push_back(4);
            dq.push_back(7);
            n--;
            m--;
          }
          dq.push_back(4);
          n--;
        } else {
          for (i = 0; i < p; i++) {
            dq.push_back(7);
            dq.push_back(4);
            n--;
            m--;
          }
          dq.push_back(7);
          m--;
        }
      }
      if (n < 0 || m < 0)
        flag = 1;
      else {
        int sz = dq.size();
        for (i = 0; i < sz; i++) {
          if (dq[i] == 4 && first == -1)
            first = i;
          else if (dq[i] == 7)
            la = i;
        }
        for (i = 0; i < sz; i++) {
          cout << dq[i];
          if (i == first) {
            while (n--) cout << '4';
          }
          if (i == la) {
            while (m--) cout << '7';
          }
        }
      }
    }
  }
  if (flag == 1) cout << "-1";
  return 0;
}
