View Compilation Error

0_0_39220313_29067.cpp:3:9: error: expected constructor, destructor, or type conversion before '(' token
    3 | freopen ( "in.txt","r", stdin) ;freopen ( "out.txt","w", stdout) ;
      |         ^
0_0_39220313_29067.cpp:3:41: error: expected constructor, destructor, or type conversion before '(' token
    3 | freopen ( "in.txt","r", stdin) ;freopen ( "out.txt","w", stdout) ;
      |                                         ^
0_0_39220313_29067.cpp: In function 'int main()':
0_0_39220313_29067.cpp:10:9: error: 'cin' was not declared in this scope
   10 |         cin >> t >> n >> m;
      |         ^~~
0_0_39220313_29067.cpp:17:20: error: 'cout' was not declared in this scope
   17 |         if (i != 1)cout << '\n';
      |                    ^~~~
0_0_39220313_29067.cpp:19:9: error: 'printf' was not declared in this scope
   19 |         printf("Case %d: %.2lf\n", i, ans / m);
      |         ^~~~~~
0_0_39220313_29067.cpp:1:1: note: 'printf' is defined in header '<cstdio>'; did you forget to '#include <cstdio>'?
  +++ |+#include <cstdio>
    1 | #define mytest