/in/foo.cc: In function 'int main()':
/in/foo.cc:9:3: warning: statement has no effect [-Wunused-value]
  s==a+b+c;
  ~^~~~~~~
/in/foo.cc:10:9: warning: 's' is used uninitialized in this function [-Wuninitialized]
  cout<<s;
         ^