module main;

import std.stdio;
import std.algorithm;
import std.range;
import std.bigint;
import std.parallelism;


const base = 100000;

BigInt factor(int base)
{
    auto cpuf = totalCPUs * 4;
    return taskPool.reduce!"a * b"(
               iota(1, base + 1)
               .chunks((base < cpuf) ? base : base / cpuf)
               .map!(fold!"cast(std.bigint.BigInt)a * b")
           );
}

int main(string[] args)
{
    writefln("%s", factor(base));
    return 0;
}

 from multiprocessing import Pool
def factorial(vector):
    result = 1
    for i in range(vector[0], vector[1]):
        result = result * i
    return result
if __name__ == '__main__':
    with Pool(4) as pool:
        total = 1
        for result in pool.map(factorial, [(1, 2501), (2501, 5001), (5001, 7501), (7501, 10001)]):
            total *= result
    print(total)

 #include <omp.h>
int main(void){
	int i,n=10;
	int fac=1;
#pragma omp parallel for shared(n) private(i) reduction(*:fac)
	for(i=1;i<=n;i++){
		fac*=i;
	}
	printf("%d\n",fac);
	return 0;
}