View Compilation Error

0_0_32724164_18369.cpp: In function 'int main()':
0_0_32724164_18369.cpp:29:30: error: 'setprecision' was not declared in this scope
   cout<<fixed<<setprecision(7)<<ans<<endl;
                              ^
0_0_32724164_18369.cpp:29:33: error: 'ans' was not declared in this scope
   cout<<fixed<<setprecision(7)<<ans<<endl;
                                 ^