foo.cc: In function 'int main()':
foo.cc:5:8: error: 'a' was not declared in this scope
  int x=a,y=b;
        ^
foo.cc:6:10: error: 'b' was not declared in this scope
  cin>>a>>b;
          ^
foo.cc:5:6: warning: unused variable 'x' [-Wunused-variable]
  int x=a,y=b;
      ^

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