foo.cc:3:5: error: cannot declare '::main' to be a global variable
    3 | int main
      |     ^~~~
foo.cc:5:9: error: expected primary-expression before 'int'
    5 |         int a,b;
      |         ^~~
foo.cc:5:9: error: expected '}' before 'int'
foo.cc:4:1: note: to match this '{'
    4 | {
      | ^
foo.cc:6:9: error: 'cin' does not name a type
    6 |         cin>>a>>b;
      |         ^~~
foo.cc:7:9: error: 'cout' does not name a type
    7 |         cout<<a+b;
      |         ^~~~
foo.cc:8:9: error: expected unqualified-id before 'return'
    8 |         return 0;
      |         ^~~~~~
foo.cc:9:1: error: expected declaration before '}' token
    9 | }
      | ^

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