View Compilation Error

0_0_30110562_19577.cpp:6:17: error: 'M_PI' was not declared in this scope
 const double pi=M_PI,g=9.8;
                 ^
0_0_30110562_19577.cpp: In function 'int main()':
0_0_30110562_19577.cpp:22:26: error: 'C' was not declared in this scope
             double t=2*S*C*v*v/g+C*v*((sqrt(S*S*v*v/g/g+2*h/g))-S*v/g);
                          ^
0_0_30110562_19577.cpp:22:32: error: 'g' was not declared in this scope
             double t=2*S*C*v*v/g+C*v*((sqrt(S*S*v*v/g/g+2*h/g))-S*v/g);
                                ^