foo.cc: In function ‘int main()’:
foo.cc:6:18: warning: right operand of comma operator has no effect [-Wunused-value]
    6 |         cin>>a,b,c;
      |                  ^
foo.cc:6:19: warning: right operand of comma operator has no effect [-Wunused-value]
    6 |         cin>>a,b,c;
      |                   ^
foo.cc:7:15: warning: ‘b’ is used uninitialized [-Wuninitialized]
    7 |         cout<<b;
      |               ^
foo.cc:5:15: note: ‘b’ was declared here
    5 |         int a,b,c;
      |               ^