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Time limit1sMemory limit1024 MB

Summary

Count the distinct ways to arrange A red, B green, and C blue cars in N parking spaces, where cars of the same color are indistinguishable.

Level: Easy3 of 10
Topics: Combinatorics, Math
Solved: No attempts yet

문제

Park $A$ red cars, $B$ green cars, and $C$ blue cars in a parking lot with $N$ spaces, one car per space. All cars are the same model and differ only in color.

Find the number of ways all cars can be parked, one car per space.

입력

The first line contains positive integers $N$ , $A$ , $B$ , and $C$ , separated by spaces.

출력

Print the answer on the first line.

제한

$A+B+C = N \leq 15$

Examples2

Example 1
Input
```
7 2 2 3
```
Expected output
```
210
```
Example 2
Input
```
8 1 2 5
```
Expected output
```
168
```