View Compilation Error

0_0_25634127_461.cpp: In function 'int main()':
0_0_25634127_461.cpp:4:18: error: 'scanf' was not declared in this scope
     scanf("%d",&t);
                  ^
0_0_25634127_461.cpp:11:25: error: 'a' was not declared in this scope
             scanf("%d",&a[i]);
                         ^
0_0_25634127_461.cpp:13:33: error: 'a' was not declared in this scope
         long long minn=sqrt(abs(a[n-1]-a[0]));
                                 ^
0_0_25634127_461.cpp:13:44: error: 'abs' was not declared in this scope
         long long minn=sqrt(abs(a[n-1]-a[0]));
                                            ^
0_0_25634127_461.cpp:13:45: error: 'sqrt' was not declared in this scope
         long long minn=sqrt(abs(a[n-1]-a[0]));
                                             ^
0_0_25634127_461.cpp:14:29: error: 'printf' was not declared in this scope
         printf("%lld\n",minn);
                             ^