View Compilation Error

0_0_18502631_29419.cpp:1:1: error: 'include' does not name a type
 include<bits/stdc++.h>
 ^
0_0_18502631_29419.cpp: In function 'int main()':
0_0_18502631_29419.cpp:14:18: error: 'scanf' was not declared in this scope
     scanf("%d",&T);
                  ^
0_0_18502631_29419.cpp:21:25: error: 'printf' was not declared in this scope
             printf("0\n"); 
                         ^
0_0_18502631_29419.cpp:31:23: error: 'sort' was not declared in this scope
         sort(a+1,a+1+n);
                       ^
0_0_18502631_29419.cpp:47:28: error: 'printf' was not declared in this scope
         printf("%.9f\n",res);
                            ^