/in/foo.cc:1:2: error: invalid preprocessing directive #cstdio
 #cstdio
  ^~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:5:23: error: 'scanf' was not declared in this scope
     scanf("%d%d",&a,&b);
                       ^
/in/foo.cc:6:22: error: 'printf' was not declared in this scope
     printf("%d%d",a+b);
                      ^