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A. The number of positions

time limit per test

0.5 secondmemory limit per test

256 megabytesinput

standard inputoutput

standard outputPetr stands in line of *n* people, but he doesn't know exactly which position he occupies. He can say that there are no less than *a* people standing in front of him and no more than *b* people standing behind him. Find the number of different positions Petr can occupy.

Input

The only line contains three integers *n*, *a* and *b* (0 ≤ *a*, *b* < *n* ≤ 100).

Output

Print the single number — the number of the sought positions.

Examples

Input

3 1 1

Output

2

Input

5 2 3

Output

3

Note

The possible positions in the first sample are: 2 and 3 (if we number the positions starting with 1).

In the second sample they are 3, 4 and 5.

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