/in/foo.cc: In function 'int main()':
/in/foo.cc:6:10: warning: right operand of comma operator has no effect [-Wunused-value]
  cin>>a,b;
          ^
/in/foo.cc:7:3: warning: 'b' is used uninitialized in this function [-Wuninitialized]
  c=a+b;
  ~^~~~