PivotOJ

Cowmpetency

시간 제한: 2000ms메모리 제한: 1024MB출처: USACO 2024 January GoldBOJ 31553

문제

Farmer John is hiring a new herd leader for his cows. To that end, he has interviewed NN (2N1092 \leq N \leq 10^9) cows for the position. After each interview, he assigned an integer "cowmpetency" score to the candidate ranging from 11 to CC (1C1041 \leq C \leq 10^4) that is correlated with their leadership abilities.

Because he has interviewed so many cows, Farmer John has forgotten all of their cowmpetency scores. However, he does remembers QQ (1Qmin(N1,100)1 \leq Q \leq \min(N - 1, 100)) pairs of numbers (ai,hi)(a_i, h_i) where cow hih_i was the first cow with a strictly greater cowmpetency score than cows 11 through aia_i (so 1ai<hiN1 \leq a_i < h_i \leq N).

Farmer John now tells you the QQ pairs of (ai,hi)(a_i, h_i). Help him count how many sequences of cowmpetency scores are consistent with this information! It is guaranteed that there is at least one such sequence. Because this number may be very large, output its value modulo 109+710^9 + 7.

입력

The first line contains NN, QQ, and CC.

The next QQ lines each contain a pair (ai,hi)(a_i, h_i). It is guaranteed that all aja_j are distinct.

출력

The number of sequences of cowmpetency scores consistent with what Farmer John remembers, modulo 109+710^9+7.

예제

예제 1

입력
6 2 3
2 3
4 5
출력
6

예제 2

입력
10 1 20
1 3
출력
399988086
코드를 제출하려면 로그인하세요.