There are several sites that can help you if you just google for scanf,
but here is the quick answer:
When you use a scanf statment you can have the user input a string of multiple values each separated by a delimiter. For example if you were asking someone to enter a date in month-day-year format you would simply code your scanf in that same format.
Code:
scanf("%d-%d-%d", &month, &day, &year);
When their input is read in the scanf ignores the delimiter that matches up with the same character in the user's input string. In your example you are just using a space as the delimiter.