foo.cc: In function 'int main()':
foo.cc:18:11: error: 'x' was not declared in this scope
   18 |         a[x][y]='#';
      |           ^
foo.cc:18:14: error: 'y' was not declared in this scope; did you mean 'yn'?
   18 |         a[x][y]='#';
      |              ^
      |              yn

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