View Compilation Error

0_0_18714101_26405.cpp: In function 'int main()':
0_0_18714101_26405.cpp:5:23: error: 'scanf' was not declared in this scope
  scanf("%d %d", &a, &b);
                       ^
0_0_18714101_26405.cpp:6:20: error: 'printf' was not declared in this scope
  printf("%d", a + b);
                    ^