/in/foo.cc:6:2: error: expected unqualified-id before ']' token
  ],aft[];
  ^
/in/foo.cc: In function 'void dfs(int, int, int, int)':
/in/foo.cc:11:18: error: 'aft' was not declared in this scope
      printf("%c",aft[ar]);
                  ^~~
/in/foo.cc:13:13: error: 'mid' was not declared in this scope
          if(mid[k]==aft[ar]){
             ^~~
/in/foo.cc:14:23: error: expected primary-expression before ',' token
              dfs(ml,k-,al,al+k-ml-);
                       ^
/in/foo.cc:14:35: error: expected primary-expression before ')' token
              dfs(ml,k-,al,al+k-ml-);
                                   ^
/in/foo.cc:15:20: error: expected primary-expression before ',' token
              dfs(k+,mr,al+k-ml,ar-);
                    ^
/in/foo.cc:15:35: error: expected primary-expression before ')' token
              dfs(k+,mr,al+k-ml,ar-);
                                   ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:23:19: error: 'mid' was not declared in this scope
      scanf("%s%s",mid,aft);
                   ^~~
/in/foo.cc:23:19: note: suggested alternative: 'main'
      scanf("%s%s",mid,aft);
                   ^~~
                   main
/in/foo.cc:23:23: error: 'aft' was not declared in this scope
      scanf("%s%s",mid,aft);
                       ^~~
/in/foo.cc:24:20: error: expected primary-expression before ';' token
      N=strlen(aft)-;
                    ^
/in/foo.cc:25:10: error: expected primary-expression before ',' token
      dfs(,N,,N);
          ^
/in/foo.cc:25:13: error: expected primary-expression before ',' token
      dfs(,N,,N);
             ^