Codeforces 124A - The number of positions
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.
範例:
input:
1 | 3 1 1 |
output:
1 | 2 |
input:
1 | 5 2 3 |
output:
1 | 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.
題意:
在n個人的隊列中，他前面有不小於a個的人；後面有不多於b個的人，問你他有幾個可能的位置？
思路:
將隊列以編號[1,n]來看，則前面有不小於a個的人表示他在[a+1,n]的位置；後面有不多於b個的人表示他在[n-b,n]的位置，取兩者的交集即可。