foo.cpp:1:2: error: invalid preprocessing directive #includ
 #includ<cstdio>
  ^
foo.cpp: In function 'int main()':
foo.cpp:23:20: error: 'scanf' was not declared in this scope
  scanf("%d%d",&a,&b);
                    ^
foo.cpp:26:15: error: 'printf' was not declared in this scope
  printf("%d",x);
               ^