View Compilation Error

0_0_33650654_21288.cpp: In function 'int main(int, const char**)':
0_0_33650654_21288.cpp:10:2: error: 'cin' was not declared in this scope
  cin>>n;
  ^
0_0_33650654_21288.cpp:21:31: error: 'sqrt' was not declared in this scope
         sum=d-0.5*t0*(a*sqrt(x)+b*sqrt(x));
                               ^
0_0_33650654_21288.cpp:22:9: error: 'cout' was not declared in this scope
         cout<<setprecision(20)<<sum<<endl;
         ^
0_0_33650654_21288.cpp:22:38: error: 'endl' was not declared in this scope
         cout<<setprecision(20)<<sum<<endl;
                                      ^