#include <iostream>

#include <algorithm>

#include <cstdio>

#define PER(i,a,n) for(int i=n;i>=a;--i)

#define REP(i,a,n) for(int i=a;i<=n;++i)

using namespace std;

typedef long long ll;

ll gcd(ll a,ll b) {return b?gcd(b,a%b):a;}

const int N = 4e5+10, INF = 0x3f3f3f3f;

int n, cnt, ans, sum;

int a[N];

char buf[N];

int main() {

	scanf("%d", &n);

	REP(i,1,n) {

		scanf("%d", a+i);

		ans = gcd(ans, a[i]);

		cnt += a[i]&1;

		sum += a[i];

	}

	if (cnt>1) {

		puts("0");

		REP(i,1,n) REP(j,1,a[i]) putchar(i-1+'a');

		return puts(""),0;

	}

	if (cnt) {

		int len = sum/ans, cur = len/2+1;

		REP(i,1,n) if (a[i]&1) {

			buf[cur] = i-1+'a';

			++cur; break;

		}

		REP(i,1,n) REP(j,1,a[i]/ans/2) buf[cur]=buf[len-cur+1]=i-1+'a',++cur;

		printf("%d\n", ans);

		REP(i,1,ans) REP(j,1,len) putchar(buf[j]);

		return puts(""),0;

	}

	int len = sum/ans*2, cur = len/2+1;

	REP(i,1,n) REP(j,1,a[i]/ans) buf[cur]=buf[len-cur+1]=i-1+'a',++cur;

	printf("%d\n", ans);

	REP(i,1,ans/2) REP(j,1,len) putchar(buf[j]);

	puts("");

}