---

Lỗi biên dịch:

Main.cc: In function ‘int main()’:
Main.cc:8:5: error: expected initializer before ‘cin’
     cin >> n;
     ^~~
Main.cc:9:21: error: ‘n’ was not declared in this scope
         float pi =  n / 3,14;
                     ^
Main.cc:9:21: note: suggested alternative: ‘yn’
         float pi =  n / 3,14;
                     ^
                     yn
Main.cc:10:5: error: ‘cout’ was not declared in this scope
     cout << pi;
     ^~~~
Main.cc:10:5: note: suggested alternative: ‘cosl’
     cout << pi;
     ^~~~
     cosl