View Compilation Error

0_0_23230307_32441.cpp: In member function 'virtual void Solution::ProcessInput()':
0_0_23230307_32441.cpp:53:20: error: 'scanf_s' was not declared in this scope
    scanf_s("%d", &n);
                    ^
0_0_23230307_32441.cpp: In function 'int main()':
0_0_23230307_32441.cpp:204:2: error: 'HDU1254' has not been declared
  HDU1254::Solution s;
  ^
0_0_23230307_32441.cpp:205:2: error: 's' was not declared in this scope
  s.ProcessInput();
  ^