View Compilation Error

0_0_20600513_23475.cpp: In function 'int main()':
0_0_20600513_23475.cpp:6:5: error: 'cin' was not declared in this scope
     cin>>casn;  
     ^
0_0_20600513_23475.cpp:10:22: error: 'scanf' was not declared in this scope
         scanf("%d",&n);  
                      ^
0_0_20600513_23475.cpp:12:25: error: 'a' was not declared in this scope
             scanf("%X",&a[j]);  
                         ^
0_0_20600513_23475.cpp:13:17: error: 'inf' was not declared in this scope
         int ans=inf;  
                 ^
0_0_20600513_23475.cpp:16:27: error: 'rand' was not declared in this scope
             int idx1=rand()%n;  
                           ^
0_0_20600513_23475.cpp:19:21: error: 'a' was not declared in this scope
             int val=a[idx1]^a[idx2];  
                     ^
0_0_20600513_23475.cpp:20:49: error: 'min' was not declared in this scope
             ans=min(ans,__builtin_popcountl(val));  
                                                 ^
0_0_20600513_23475.cpp:22:9: error: 'cout' was not declared in this scope
         cout<<ans<<endl;  
         ^
0_0_20600513_23475.cpp:22:20: error: 'endl' was not declared in this scope
         cout<<ans<<endl;  
                    ^