foo.cc: In function 'int main()':
foo.cc:6:16: error: 'o' was not declared in this scope
    6 |         char b=o;
      |                ^
foo.cc:8:9: error: 'cin' was not declared in this scope
    8 |         cin>>a;
      |         ^~~
foo.cc:11:16: error: expected primary-expression before ')' token
   11 |         if(b==+)
      |                ^
foo.cc:13:9: error: 'cout' was not declared in this scope
   13 |         cout<<(a+c)<<endl;
      |         ^~~~
foo.cc:13:22: error: 'endl' was not declared in this scope
   13 |         cout<<(a+c)<<endl;
      |                      ^~~~
foo.cc:15:21: error: expected primary-expression before ')' token
   15 |         else if(b==-)
      |                     ^
foo.cc:17:9: error: 'cout' was not declared in this scope
   17 |         cout<<(a-c)<<endl;
      |         ^~~~
foo.cc:17:22: error: 'endl' was not declared in this scope
   17 |         cout<<(a-c)<<endl;
      |                      ^~~~

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