foo.cpp: In function 'void init()':
foo.cpp:11:15: error: 'scanf' was not declared in this scope
  scanf("%d",&n);
               ^
foo.cpp: In function 'void dp()':
foo.cpp:34:19: error: 'printf' was not declared in this scope
  printf("%d\n",ans);
                   ^
foo.cpp: In function 'int main()':
foo.cpp:38:6: warning: unused variable 'i' [-Wunused-variable]
 {int i;
      ^