Language: C++

#include<stdio.h>
using namespace std;
int main(){
  string s;
  cin >> s;
  if(s=="SUN"){
    cout << 7 << endl;
  }
  if(s=="MON"){
    cout << 6 << endl;
  }
  if(s=="TUE"){
    cout << 5 << endl;
  }
  if(s=="WED"){
    cout << 4 << endl;
  }
  if(s=="THU"){
    cout << 3 << endl;
  }
  if(s=="FRI"){
    cout << 2 << endl;
  }
  if(s=="SAT"){
    cout << 1 << endl;
  }
}

Compiler output:
a.cc: In function 'int main()':
a.cc:4:3: error: 'string' was not declared in this scope
    4 |   string s;
      |   ^~~~~~
a.cc:2:1: note: 'std::string' is defined in header '<string>'; this is probably fixable by adding '#include <string>'
    1 | #include<stdio.h>
  +++ |+#include <string>
    2 | using namespace std;
a.cc:5:3: error: 'cin' was not declared in this scope
    5 |   cin >> s;
      |   ^~~
a.cc:2:1: note: 'std::cin' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
    1 | #include<stdio.h>
  +++ |+#include <iostream>
    2 | using namespace std;
a.cc:5:10: error: 's' was not declared in this scope
    5 |   cin >> s;
      |          ^
a.cc:7:5: error: 'cout' was not declared in this scope
    7 |     cout << 7 << endl;
      |     ^~~~
a.cc:7:5: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:7:18: error: 'endl' was not declared in this scope
    7 |     cout << 7 << endl;
      |                  ^~~~
a.cc:2:1: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
    1 | #include<stdio.h>
  +++ |+#include <ostream>
    2 | using namespace std;
a.cc:10:5: error: 'cout' was not declared in this scope
   10 |     cout << 6 << endl;
      |     ^~~~
a.cc:10:5: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:10:18: error: 'endl' was not declared in this scope
   10 |     cout << 6 << endl;
      |                  ^~~~
a.cc:10:18: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:13:5: error: 'cout' was not declared in this scope
   13 |     cout << 5 << endl;
      |     ^~~~
a.cc:13:5: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:13:18: error: 'endl' was not declared in this scope
   13 |     cout << 5 << endl;
      |                  ^~~~
a.cc:13:18: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:16:5: error: 'cout' was not declared in this scope
   16 |     cout << 4 << endl;
      |     ^~~~
a.cc:16:5: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:16:18: error: 'endl' was not declared in this scope
   16 |     cout << 4 << endl;
      |                  ^~~~
a.cc:16:18: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:19:5: error: 'cout' was not declared in this scope
   19 |     cout << 3 << endl;
      |     ^~~~
a.cc:19:5: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:19:18: error: 'endl' was not declared in this scope
   19 |     cout << 3 << endl;
      |                  ^~~~
a.cc:19:18: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:22:5: error: 'cout' was not declared in this scope
   22 |     cout << 2 << endl;
      |     ^~~~
a.cc:22:5: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:22:18: error: 'endl' was not declared in this scope
   22 |     cout << 2 << endl;
      |                  ^~~~
a.cc:22:18: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'
a.cc:25:5: error: 'cout' was not declared in this scope
   25 |     cout << 1 << endl;
      |     ^~~~
a.cc:25:5: note: 'std::cout' is defined in header '<iostream>'; this is probably fixable by adding '#include <iostream>'
a.cc:25:18: error: 'endl' was not declared in this scope
   25 |     cout << 1 << endl;
      |                  ^~~~
a.cc:25:18: note: 'std::endl' is defined in header '<ostream>'; this is probably fixable by adding '#include <ostream>'