Language: C++

using namespace std;
int main()
{
	char a[4];
	cin.getline(a,4);
	if(!strcmp(a,"MON"))
		cout<<6<<endl;
	else if(!strcmp(a,"TUE"))
		cout<<5<<endl;
	else if(!strcmp(a,"WED"))
		cout<<4<<endl;
	else if(!strcmp(a,"THU"))
		cout<<3<<endl;
	else if(!strcmp(a,"FRI"))
		cout<<2<<endl;
	else if(!strcmp(a,"SAT"))
		cout<<1<<endl;
	else if(!strcmp(a,"SUN"))
		cout<<7<<endl;
	else
		return 0;
	return 0;


}

Compiler output:
a.cc: In function 'int main()':
a.cc:5:9: error: 'cin' was not declared in this scope
    5 |         cin.getline(a,4);
      |         ^~~
a.cc:1:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
  +++ |+#include <iostream>
    1 | using namespace std;
a.cc:6:13: error: 'strcmp' was not declared in this scope
    6 |         if(!strcmp(a,"MON"))
      |             ^~~~~~
a.cc:1:1: note: 'strcmp' is defined in header '<cstring>'; this is probably fixable by adding '#include <cstring>'
  +++ |+#include <cstring>
    1 | using namespace std;
a.cc:7:17: error: 'cout' was not declared in this scope
    7 |                 cout<<6<<endl;
      |                 ^~~~
a.cc:7:17: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:7:26: error: 'endl' was not declared in this scope
    7 |                 cout<<6<<endl;
      |                          ^~~~
a.cc:1:1: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
  +++ |+#include <ostream>
    1 | using namespace std;
a.cc:9:17: error: 'cout' was not declared in this scope
    9 |                 cout<<5<<endl;
      |                 ^~~~
a.cc:9:17: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:9:26: error: 'endl' was not declared in this scope
    9 |                 cout<<5<<endl;
      |                          ^~~~
a.cc:9:26: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:11:17: error: 'cout' was not declared in this scope
   11 |                 cout<<4<<endl;
      |                 ^~~~
a.cc:11:17: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:11:26: error: 'endl' was not declared in this scope
   11 |                 cout<<4<<endl;
      |                          ^~~~
a.cc:11:26: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:13:17: error: 'cout' was not declared in this scope
   13 |                 cout<<3<<endl;
      |                 ^~~~
a.cc:13:17: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:13:26: error: 'endl' was not declared in this scope
   13 |                 cout<<3<<endl;
      |                          ^~~~
a.cc:13:26: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:15:17: error: 'cout' was not declared in this scope
   15 |                 cout<<2<<endl;
      |                 ^~~~
a.cc:15:17: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:15:26: error: 'endl' was not declared in this scope
   15 |                 cout<<2<<endl;
      |                          ^~~~
a.cc:15:26: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:17:17: error: 'cout' was not declared in this scope
   17 |                 cout<<1<<endl;
      |                 ^~~~
a.cc:17:17: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:17:26: error: 'endl' was not declared in this scope
   17 |                 cout<<1<<endl;
      |                          ^~~~
a.cc:17:26: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:19:17: error: 'cout' was not declared in this scope
   19 |                 cout<<7<<endl;
      |                 ^~~~
a.cc:19:17: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:19:26: error: 'endl' was not declared in this scope
   19 |                 cout<<7<<endl;
      |                          ^~~~
a.cc:19:26: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'