foo.cc: In function 'int main()':
foo.cc:28:25: error: 'n' was not declared in this scope
   28 |                         n++;
      |                         ^
foo.cc:29:17: error: 'n' was not declared in this scope
   29 |         while(i<n)
      |                 ^
foo.cc:23:14: warning: unused variable 'ws' [-Wunused-variable]
   23 |         char ws[100001];
      |              ^~

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