/in/foo.cc: In function 'int main()':
/in/foo.cc:6:16: warning: right operand of comma operator has no effect [-Wunused-value]
  cin>>xmin,xmax;
                ^
/in/foo.cc:7:8: warning: unused variable 'b' [-Wunused-variable]
  int a,b,c,d;
        ^
/in/foo.cc:8:3: warning: 'xmax' is used uninitialized in this function [-Wuninitialized]
  a=xmax-xmin;
  ~^~~~~~~~~~
/in/foo.cc:15:9: warning: 'd' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<d;
         ^