>
> #include <iostream>
> #include <cstring>
> #include <cstdio>
> #include <string>
> 
> #define MaxN 2005
> 
> using namespace std;
> 
> char str[MaxN];
> char res[MaxN];
> int n;
> 
> int main()
> {
> 
>     while(scanf("%d", &n) != EOF) {
>         for(int i = 0; i < n; i++) {
>             char c;
>             cin >> c;
>             str[i] = c;
>         }
>         str[n] = 0;
>         int i = 0; 
>         int j = n - 1;
>         int k = 0;
>         while(i < j) {
>             if(str[i] < str[j]) {
>                 res[k] = str[i];
>                 i++;
>             }
>             else if(str[i] > str[j]){
>                 res[k] = str[j];
>                 j--;
>             }
>             else {
>                 int x = i + 1, y = j - 1;
>                 while(x < y && str[x] == str[y]) {
>                     x++;
>                     y--;
>                 }
>                 if(str[x] < str[y]) {
>                     res[k] = str[i];
>                     i++;
>                 }
>                 else {
>                     res[k] = str[j];
>                     j--;
>                 }
>             }
>             k++;
>         }
>         res[n-1] = str[i];
>         res[n] = 0;
>         int ans = 0;
>         for(int i = 0; i < n; i++) {
>             printf("%c", res[i]);
>             ans++;
>             if(ans % 80 == 0 && i < n - 1)
>                 printf("\n");
>         }
>     }
>     return 0;
> }