View Compilation Error

0_0_30277694_30858.cpp: In function 'int main()':
0_0_30277694_30858.cpp:39:40: error: 'floor' was not declared in this scope
                 sum += floor(a[i] / mid);
                                        ^
0_0_30277694_30858.cpp:10:21: error: 'acos' was not declared in this scope
 #define PI acos(-1.0)
                     ^
0_0_30277694_30858.cpp:45:52: note: in expansion of macro 'PI'
         cout << fixed << setprecision(4) << left * PI << endl;
                                                    ^