1 #include <bits/stdc++.h>
  2 
  3 using namespace std;
  4 
  5 const int N = 2005;
  6 
  7 int n, num[N];
  8 
  9 int low[N], col[N];
 10 
 11 int hd[N], to[N], nt[N], tot;
 12 
 13 void addEdge(int x, int y)
 14 {
 15     nt[++tot] = hd[x]; to[tot] = y; hd[x] = tot;
 16     nt[++tot] = hd[y]; to[tot] = x; hd[y] = tot;
 17 }
 18 
 19 bool dfs(int u, int c)
 20 {
 21     if (col[u] != -1)
 22         return col[u] != c;
 23 
 24     col[u] = c;
 25     
 26     for (int i = hd[u]; i; i = nt[i])
 27         if (dfs(to[i], c ^ 1))return true;
 28         
 29     return false;
 30 }
 31 
 32 int stk1[N], tot1;
 33 int stk2[N], tot2;
 34 int ans[N], cnt, t(1);
 35 
 36 void pop(void)
 37 {
 38     if (tot1 && stk1[tot1] == t)
 39         { ans[++cnt] = 1, --tot1, ++t; pop(); }
 40     if (tot2 && stk2[tot2] == t)
 41         { ans[++cnt] = 3, --tot2, ++t; pop(); }
 42 }
 43 
 44 void putAns(void)
 45 {
 46     for (int i = 1; i <= n; ++i)
 47     {
 48         pop();
 49         
 50         switch (col[i])
 51         {
 52             case 0: 
 53             {
 54                 stk1[++tot1] = num[i];
 55                 ans[++cnt] = 0;
 56                 break;
 57             }
 58             case 1:
 59             {
 60                 stk2[++tot2] = num[i];
 61                 ans[++cnt] = 2;
 62                 break;
 63             }
 64         }
 65     }
 66     
 67     pop();
 68     
 69     for (int i = 1; i <= cnt; ++i)
 70         printf("%c ", ‘a‘ + ans[i]);
 71 }
 72 
 73 signed main(void)
 74 {
 75     scanf("%d", &n);
 76     
 77     for (int i = 1; i <= n; ++i)
 78         scanf("%d", num + i);
 79         
 80     low[n] = num[n];
 81         
 82     for (int i = n; i >= 2; --i)
 83         low[i - 1] = min(num[i], low[i]);
 84         
 85     for (int i = 1; i < n; ++i)
 86         for (int j = 1 + i; j <= n; ++j)
 87             if (num[i] < num[j] && num[i] > low[j])
 88                 addEdge(i, j);
 89                 
 90     bool flag = true;
 91     
 92     memset(col, -1, sizeof(col));
 93     
 94     for (int i = 1; i <= n; ++i)
 95         if (col[i] == -1)if (dfs(i, 0))
 96             { flag = false; break; }
 97             
 98     if (flag)
 99         putAns();
100     else
101         puts("0");
102 }