#include <bits/stdc++.h>
#pragma comment(linker, "/STACK:16777216")
using namespace std;
const int INF = 1e9;
const double Pi = acos(-1.0);
const long double Eps = 1e-8;
const int MAXN = 4e6;
char ans[MAXN + 1];
int len = 0;
int main() {
  int a[4];
  for (int i = 0; i < 4; i++) scanf("%d", a + i);
  if (abs(a[2] - a[3]) > 1) {
    puts("-1");
    return 0;
  }
  int four, seven;
  if (a[2] > a[3]) {
    four = a[0] - a[2];
    seven = a[1] - a[2];
    if (four < 0 || seven < 0) {
      puts("-1");
      return 0;
    }
    for (int i = 0; i < four; i++) ans[len++] = '4';
    for (int i = 0; i < a[2]; i++) {
      ans[len++] = '4';
      ans[len++] = '7';
    }
    for (int i = 0; i < seven; i++) ans[len++] = '7';
  } else if (a[2] < a[3]) {
    four = a[0] - a[3];
    seven = a[1] - a[3];
    if (four < 0 || seven < 0) {
      puts("-1");
      return 0;
    }
    if (a[3] == 1) {
      for (int i = 0; i < seven; i++) ans[len++] = '7';
      ans[len++] = '7';
      ans[len++] = '4';
      for (int i = 0; i < four; i++) ans[len++] = '4';
    } else {
      ans[len++] = '7';
      for (int i = 0; i < four + 1; i++) ans[len++] = '4';
      for (int i = 0; i < a[3] - 2; i++) {
        ans[len++] = '7';
        ans[len++] = '4';
      }
      for (int i = 0; i < seven + 1; i++) ans[len++] = '7';
      ans[len++] = '4';
    }
  } else {
    four = a[0] - a[2];
    seven = a[1] - a[2];
    if (four < 0 || seven < 0 || !four && !seven) {
      puts("-1");
      return 0;
    }
    if (four) {
      for (int i = 0; i < four - 1; i++) ans[len++] = '4';
      for (int i = 0; i < a[2] - 1; i++) {
        ans[len++] = '4';
        ans[len++] = '7';
      }
      ans[len++] = '4';
      for (int i = 0; i < seven + 1; i++) ans[len++] = '7';
      ans[len++] = '4';
    } else {
      for (int i = 0; i < a[3]; i++) {
        ans[len++] = '7';
        ans[len++] = '4';
      }
      for (int i = 0; i < seven; i++) ans[len++] = '7';
    }
  }
  ans[len] = '\0';
  puts(ans);
  return 0;
}
