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#1264. 低级算法

統計

给定一个包含 $1$ 到 $1000$ 之间整数的集合 $A$。你的任务是找出有多少个正整数可以表示为 $A$ 中若干元素的和,且加数的个数在 $\ell$ 到 $r$ 之间(包含 $\ell$ 和 $r$)。允许使用相同的加数。注意,每个数字只计算一次,即使它有多种表示方式。

输入格式

第一行包含三个空格分隔的整数:$n$(集合 $A$ 中元素的个数,$1 \le n \le 1000$),以及 $\ell$ 和 $r$(加数个数的范围,$1 \le \ell \le r \le 2000$)。第二行包含 $n$ 个空格分隔的整数 $a_1, a_2, \dots, a_n$($1 \le a_1 < a_2 < \dots < a_n \le 1000$):集合 $A$ 中的元素,按升序排列。

输出格式

输出可以表示为 $A$ 中若干元素之和,且加数个数在 $\ell$ 到 $r$ 之间的整数的个数。

样例

样例输入 1

2 1 2
1 2

样例输出 1

4

样例输入 2

3 1 3
1 3 10

样例输出 2

18

样例输入 3

6 3 5
1 2 3 4 5 6

样例输出 3

28

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