View Compilation Error

0_0_23287938_22166.cpp: In function 'int func(long int)':
0_0_23287938_22166.cpp:5:22: error: 'sqrt' was not declared in this scope
   double sqrtm=sqrt(a);
                      ^
0_0_23287938_22166.cpp: In function 'int main(int, char**)':
0_0_23287938_22166.cpp:21:3: error: 'cin' was not declared in this scope
   cin>>i;
   ^
0_0_23287938_22166.cpp:32:3: error: 'cout' was not declared in this scope
   cout<<sum<<endl;
   ^
0_0_23287938_22166.cpp:32:14: error: 'endl' was not declared in this scope
   cout<<sum<<endl;
              ^