1 #include <cstdio>
2 using namespace std;
3
4 #define MAX_NUMBER 100000
5 //快速幂求x^n%mod
6 long long quick_pow(long long x, long long n, long long mod)
7 {
8 long long res = 1;
9 while (n)
10 {
11 if (n & 1)
12 {
13 res = res * x % mod;
14 }
15
16 x = x * x % mod;
17 n >>= 1;
18 }
19
20 return res;
21 }
22
23 long long fac[MAX_NUMBER+5];
24 long long n, m, p;
25
26 int main()
27 {
28 while (~scanf("%lld %lld %lld", &n, &m, &p))
29 {
30 //预处理求fac，fac[i] = i!%p
31 fac[0] = 1;
32 for (int i = 1; i <= n; i++)
33 {
34 fac[i] = fac[i - 1] * i % p;
35 }
36 //组合数 = n!*(m!%p的逆元)*((n-m)!%p的逆元)%p
37 printf("%lld\n", fac[n] * quick_pow(fac[m], p - 2, p) % p * quick_pow(fac[n - m], p - 2, p) % p);
38 }
39 }
