#include <bits/stdc++.h>
using namespace std;
int n;
int a[101];
bool checkeven(int x) {
  for (int i = 1; i <= n; i++)
    if (a[i] % (2 * x)) return false;
  printf("%d\n", 2 * x);
  for (int r = 1; r <= x; r++) {
    for (int i = 1; i <= n; i++)
      for (int j = 1; j <= a[i] / (2 * x); j++) printf("%c", i - 1 + 'a');
    for (int i = n; i >= 1; i--)
      for (int j = 1; j <= a[i] / (2 * x); j++) printf("%c", i - 1 + 'a');
  }
  return true;
}
bool checkadd(int x, int id) {
  for (int i = 1; i <= n; i++)
    if (a[i] % (2 * x)) return false;
  printf("%d\n", x);
  for (int r = 1; r <= x; r++) {
    printf("%c", (id - 1) + 'a');
    for (int i = 1; i <= n; i++)
      for (int j = 1; j <= a[i] / (2 * x); j++) printf("%c", i - 1 + 'a');
    for (int i = n; i >= 1; i--)
      for (int j = 1; j <= a[i] / (2 * x); j++) printf("%c", i - 1 + 'a');
  }
  return true;
}
int main() {
  int sum = 0, mx;
  scanf("%d", &n);
  for (int i = 1; i <= n; i++) {
    scanf("%d", &a[i]), sum += a[i];
    if (a[i] & 1) mx = max(mx, a[i]);
  }
  if (sum % 2 == 0) {
    int g = sum / 2;
    int ans = 0;
    for (int i = g; i >= 1; i--)
      if (checkeven(i)) {
        ans = 2 * i;
        break;
      }
    if (!ans) {
      printf("0\n");
      for (int i = 1; i <= n; i++)
        for (int j = 1; j <= a[i]; j++) printf("%c", i - 1 + 'a');
    }
  } else {
    int ans = 0;
    for (int j = mx; j >= 1; j -= 2) {
      for (int i = 1; i <= n; i++)
        if ((a[i] & 1) && a[i] >= j) {
          a[i] -= j;
          if (checkadd(j, i)) {
            ans = j;
            break;
          }
          a[i] += j;
        }
      if (ans) break;
    }
    if (!ans) {
      printf("0\n");
      for (int i = 1; i <= n; i++)
        for (int j = 1; j <= a[i]; j++) printf("%c", i - 1 + 'a');
    }
  }
  return 0;
}
