/in/foo.cc: In function 'int main()':
/in/foo.cc:6:11: warning: right operand of comma operator has no effect [-Wunused-value]
  cin>>a,b,c;
           ^
/in/foo.cc:6:12: warning: right operand of comma operator has no effect [-Wunused-value]
  cin>>a,b,c;
            ^
/in/foo.cc:7:12: warning: 'b' is used uninitialized in this function [-Wuninitialized]
  n=100*a+10*b+c;
          ~~^~
/in/foo.cc:7:3: warning: 'c' is used uninitialized in this function [-Wuninitialized]
  n=100*a+10*b+c;
  ~^~~~~~~~~~~~~