#!/usr/bin/perl -w

use Math::BigInt;

sub factorial_BigInt {
    my ($n, $i) = shift;
    my $result = Math::BigInt->new("1");
    return 1 if $n < 1;
    for ($i = 2; $i <= $n; $i++) {
        $result *= $i;
    }
    return $result;
}

print factorial_BigInt(1000);