Run id: 143520

Main.cc: In function 'int main()':
Main.cc:8:5: error: 'cin' was not declared in this scope
     cin >> r;
     ^
Main.cc:9:5: error: 'cout' was not declared in this scope
     cout << fixed << setprecision(3) << pi*r*r << endl;
     ^
Main.cc:9:51: error: 'endl' was not declared in this scope
     cout << fixed << setprecision(3) << pi*r*r << endl;
                                                   ^