/in/foo.c: In function 'main':
/in/foo.c:6:13: error: expected expression before ':' token
    6 |         std::cin>>a>>b;
      |             ^
/in/foo.c:7:9: error: duplicate label 'std'
    7 |         std::cout<<a+b;
      |         ^~~
/in/foo.c:6:9: note: previous definition of 'std' with type 'void'
    6 |         std::cin>>a>>b;
      |         ^~~
/in/foo.c:7:13: error: expected expression before ':' token
    7 |         std::cout<<a+b;
      |             ^
/in/foo.c:6:9: warning: label 'std' defined but not used [-Wunused-label]
    6 |         std::cin>>a>>b;
      |         ^~~
/in/foo.c:5:15: warning: unused variable 'b' [-Wunused-variable]
    5 |         int a,b;
      |               ^
/in/foo.c:5:13: warning: unused variable 'a' [-Wunused-variable]
    5 |         int a,b;
      |             ^