/in/foo.cc: In function 'int main()':
/in/foo.cc:7:6: warning: 'a' is used uninitialized in this function [-Wuninitialized]
  d=(a+b+c)/3;
     ~^~
/in/foo.cc:7:6: warning: 'b' is used uninitialized in this function [-Wuninitialized]
/in/foo.cc:7:8: warning: 'c' is used uninitialized in this function [-Wuninitialized]
  d=(a+b+c)/3;
    ~~~~^~~