foo.c: In function ‘main’:
foo.c:6:9: error: ‘cin’ undeclared (first use in this function); did you mean ‘min’?
    6 |         cin>>a>>b>>c;
      |         ^~~
      |         min
foo.c:6:9: note: each undeclared identifier is reported only once for each function it appears in
foo.c:9:13: error: ‘cout’ undeclared (first use in this function)
    9 |             cout<<a<<"<"<<b<<"<"<<c<<endl;  // 1 2 3
      |             ^~~~
foo.c:9:38: error: ‘endl’ undeclared (first use in this function)
    9 |             cout<<a<<"<"<<b<<"<"<<c<<endl;  // 1 2 3
      |                                      ^~~~
foo.c:22:48: error: ‘end1’ undeclared (first use in this function)
   22 |                       cout<<c<<"<"<<b<<"<"<<a<<end1;  // 3 2 1
      |                                                ^~~~
foo.c:5:15: warning: unused variable ‘min’ [-Wunused-variable]
    5 |     int a,b,c,min;
      |               ^~~