View Compilation Error

0_0_27562698_8328.cpp: In function 'int main()':
0_0_27562698_8328.cpp:5:19: error: 'a' was not declared in this scope
  scanf_s("%d %d",&a, &b);
                   ^
0_0_27562698_8328.cpp:5:23: error: 'b' was not declared in this scope
  scanf_s("%d %d",&a, &b);
                       ^
0_0_27562698_8328.cpp:5:24: error: 'scanf_s' was not declared in this scope
  scanf_s("%d %d",&a, &b);
                        ^