View Compilation Error

0_0_31152128_3525.cpp:7:28: error: 'acos' was not declared in this scope
 const double pi = acos(-1.0);
                            ^
0_0_31152128_3525.cpp:8:9: error: 'pair' does not name a type
 typedef pair<int, int> Pii;
         ^
0_0_31152128_3525.cpp: In function 'double aaa(double)':
0_0_31152128_3525.cpp:14:32: error: 'sqrt' was not declared in this scope
     return  sqrt((9*n*v)/2/md/g);
                                ^
0_0_31152128_3525.cpp: In function 'int main()':
0_0_31152128_3525.cpp:23:31: error: 'scanf' was not declared in this scope
     scanf("%lf%lf%lf",&u,&t,&v);
                               ^
0_0_31152128_3525.cpp:24:33: error: 'sqrt' was not declared in this scope
     double A = 18*pi/sqrt(2*md*g);
                                 ^
0_0_31152128_3525.cpp:29:34: error: 'pow' was not declared in this scope
     printf("%.20lf",A*pow(B*C,1.5)*D*1e19);
                                  ^
0_0_31152128_3525.cpp:29:42: error: 'printf' was not declared in this scope
     printf("%.20lf",A*pow(B*C,1.5)*D*1e19);
                                          ^