File size: 1,830 Bytes
c4b0eef |
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 |
/*
****************************************************************
****************************************************************
-> Coded by Stavros Chryselis
-> Visit my github for more solved problems over multiple sites
-> https://github.com/StavrosChryselis
-> Feel free to email me at [email protected]
****************************************************************
****************************************************************
*/
#include <stdio.h>
#include <ctype.h>
#include <stdlib.h>
#define gc() getchar()
#define MAXN 1000000
using namespace std;
const long long MOD = 1000000007;
long long fact[1000007];
long long N, A, B, D;
inline long long modpow(long long base, long long exp, long long modulus)
{
long long result = 1;
base %= modulus;
while (exp > 0)
{
if (exp & 1)
result = (result * base) % modulus;
base = (base * base) % modulus;
exp >>= 1;
}
return result;
}
inline bool finish()
{
char c = gc();
while (isspace(c))
c = gc();
if (c == EOF)
{
ungetc(c, stdin);
return 1;
}
ungetc(c, stdin);
return 0;
}
inline void pre()
{
int i;
fact[0] = 1;
for (i = 1; i <= MAXN; i++)
{
fact[i] = fact[i - 1] * i;
fact[i] %= MOD;
}
}
inline long long rev(long long num)
{
return modpow(num, MOD - 2, MOD);
}
inline long long ncr(long long n, long long k)
{
long long res = fact[n];
res *= rev(fact[k]);
res %= MOD;
res *= rev(fact[n - k]);
res %= MOD;
return res;
}
inline void init()
{
scanf("%lld %lld %lld %lld", &N, &A, &B, &D);
}
inline long long solve()
{
long long res = ncr(N, A);
res *= modpow(ncr(B, D), A, MOD);
res %= MOD;
return res;
}
int main()
{
// freopen("input.txt", "r", stdin);
pre();
while (!finish())
{
init();
printf("%lld\n", solve());
}
return 0;
}
|