#include <bits/stdc++.h>
using namespace std;
int N;
int cnt[30];
int gcd(int a, int b) {
  while (a && b) {
    if (a < b) swap(a, b);
    a %= b;
  }
  return a + b;
}
void f1() {
  for (int Ni = 0; Ni < N; Ni++)
    for (int ci = 0; ci < cnt[Ni]; ci++) putchar('a' + Ni);
}
void f2() {
  for (int Ni = N - 1; Ni >= 0; Ni--)
    for (int ci = 0; ci < cnt[Ni]; ci++) putchar('a' + Ni);
}
void sol(int f = -1) {
  f1();
  if (f != -1) putchar('a' + f);
  f2();
}
int main() {
  scanf("%d", &N);
  int GCD = 0;
  for (int Ni = 0; Ni < N; Ni++) {
    scanf("%d", &cnt[Ni]);
    GCD = gcd(GCD, cnt[Ni]);
  }
  for (int Ni = 0; Ni < N; Ni++) cnt[Ni] /= GCD;
  if (GCD % 2 == 0) {
    printf("%d\n", GCD);
    for (int Gi = 0; Gi < GCD; Gi += 2) sol();
  } else {
    int c = 0, d = -1;
    for (int Ni = 0; Ni < N; Ni++)
      if (cnt[Ni] & 1) c++, d = Ni;
    if (c > 1) {
      puts("0");
      for (int Gi = 0; Gi < GCD; Gi++) f1();
    } else {
      printf("%d\n", GCD);
      if (d != -1) cnt[d]--;
      for (int Ni = 0; Ni < N; Ni++) cnt[Ni] /= 2;
      for (int Gi = 0; Gi < GCD; Gi++) sol(d);
    }
  }
  puts("");
}
