Time/Memory Limit:1000 MS/32768 K

Submitted: 159 Accepted: 65

Submitted: 159 Accepted: 65

### Problem Description

Petr 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.

### Sample Input

3 1 1

### Sample Output

2

### Author

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