View Compilation Error

0_0_35656937_31310.cpp: In function 'int main()':
0_0_35656937_31310.cpp:11:11: error: 'cin' was not declared in this scope
     while(cin>>m>>n)
           ^
0_0_35656937_31310.cpp:19:80: error: 'sort' was not declared in this scope
         sort(a+1,a+n+1,[=](node x,node y) -> bool {return x.single > y.single;});//lamba表达式作为cmp函数
                                                                                ^
0_0_35656937_31310.cpp:34:29: error: 'printf' was not declared in this scope
         printf("%.3lf\n",ans);
                             ^