View Compilation Error

0_0_16048607_14718.cpp: In function 'int main()':
0_0_16048607_14718.cpp:5:22: error: 'scanf' was not declared in this scope
  while(scanf("%d", &n) && n)
                      ^
0_0_16048607_14718.cpp:11:18: error: 'abs' was not declared in this scope
     if(abs(num[i]) < abs(num[j]))
                  ^
0_0_16048607_14718.cpp:19:26: error: 'printf' was not declared in this scope
     printf("%d\n", num[i]);
                          ^
0_0_16048607_14718.cpp:21:25: error: 'printf' was not declared in this scope
     printf("%d ", num[i]);
                         ^