foo.cc: In function 'int main()':
foo.cc:4:2: error: 'cin' was not declared in this scope
    4 |  cin>>a;
      |  ^~~
foo.cc:8:7: error: 'b3' was not declared in this scope; did you mean 'b'?
    8 |  if(a=b3)
      |       ^~
      |       b
foo.cc:10:1: error: expected primary-expression before '}' token
   10 | }
      | ^
foo.cc:3:14: warning: unused variable 'sum' [-Wunused-variable]
    3 |  int a,b,c,d,sum;
      |              ^~~

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