#include <bits/stdc++.h>
using namespace std;
const int maxn = 2e5 + 10;
const int maxm = 1e3 + 5;
const int mod = 1e9 + 7;
const int inf = 0x3f3f3f3f;
int a[maxn], ans[maxn], l[maxn][6], r[maxn][6];
inline void solve() {
  int n;
  scanf("%d", &n);
  for (int i = 1; i < n + 1; i++) scanf("%d", &a[i]);
  memset(l, -1, sizeof l);
  memset(r, -1, sizeof r);
  if (a[1] > 1) {
    puts("-1");
    exit(0);
  }
  l[1][1] = r[1][1] = 1;
  for (int i = 2; i < n + 1; i++) {
    for (int j = 2; j < 5 + 1; j++) {
      if (l[i - 1][j - 1] != -1) {
        l[i][j] = l[i - 1][j - 1];
        r[i][j] = r[i - 1][j - 1];
      }
    }
    for (int j = 2; j < 5 + 1; j++) {
      if (l[i - 1][j] != -1) {
        if (l[i][1] == -1) l[i][1] = inf;
        l[i][1] = min(l[i][1], l[i - 1][j] + 1);
        r[i][1] = max(r[i][1], r[i - 1][j] + 1);
      }
    }
    if (a[i]) {
      for (int j = 1; j < 5 + 1; j++) {
        if (l[i][j] != -1) {
          if (l[i][j] <= a[i] && a[i] <= r[i][j])
            l[i][j] = r[i][j] = a[i];
          else
            l[i][j] = r[i][j] = -1;
        } else
          r[i][j] = -1;
      }
    }
    bool ok = 0;
    for (int j = 1; j < 5 + 1; j++) {
      if (l[i][j] <= r[i][j] && l[i][j] != -1) {
        ok = 1;
        break;
      }
    }
    if (!ok) {
      puts("-1");
      exit(0);
    }
  }
  int up = 0, j = 2;
  for (int i = 2; i < 5 + 1; i++) {
    if (l[n][i] <= r[n][i] && l[n][i] != -1) {
      if (r[n][i] > up) {
        up = r[n][i];
        j = i;
      }
    }
  }
  if (up == 0) {
    puts("-1");
    exit(0);
  }
  printf("%d\n", up);
  int m = n;
  while (m) {
    for (int i = m - j; i < m + 1; i++) ans[i] = up;
    m -= j;
    up--;
    for (int i = 2; i < 5 + 1; i++) {
      if (l[m][i] <= up && up <= r[m][i]) j = i;
    }
  }
  for (int i = 1; i < n + 1; i++) {
    if (i == 1)
      printf("%d", ans[i]);
    else
      printf(" %d", ans[i]);
  }
  puts("");
}
int main() {
  solve();
  return 0;
}
