foo.cc: In function 'std::string removeChar(std::string)':
foo.cc:6:21: warning: unused variable 'i' [-Wunused-variable]
    6 |  int len=s.length(),i;
      |                     ^
foo.cc: In function 'int main()':
foo.cc:19:7: error: 'ch' was not declared in this scope
   19 |  cin>>ch;
      |       ^~

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