PROGRAMMING:all round player

It is known that there are $$n $$ball players, among which:
$$a $$can play basketball, $$B $$can play volleyball, $$C $$can play football;
$$p $$people can play basketball and volleyball, $$q $$people can play basketball and football, $$R $$people can play volleyball and football.
Excuse me: what is the number of people in the three ball cities?
####Input format
>N, a, B, C, P, Q and R
####Output format
> x
####Input sample
```in
38 20 17 26 7 12 11
```
####Output sample
```out
five
```







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