rt，以下是代码：

#include <bits/stdc++.h>
//#define mod 998244353
using ll = long long;
using namespace std;
const int maxn = 5005,mod = 998244353;
int n;
ll a[maxn],b[maxn];
int ans = (mod + 1) / 2;
ll gcd(ll x,ll y)
{
	if (y == 0)return x;
	return gcd(y,x % y);
}
ll qpow(int a,int b)
{
	ll res = 1ll;
	while (b)
	{
		if (b & 1)	
			res = res * a % mod;
		a = (a * a) % mod,b >>= 1;
	}
	return res;
}
int main()
{
	scanf("%d",&n);
	for (int i = 1;i <= n;i++)	
		scanf("%lld",a + i);
	//b[1] = a[1] % mod;
	for (int i = 1;i <= n;i++)
	{
		ll cnt = 1ll;
		for (int j = 1;j < i;j++)	
		{cnt = (__int128)cnt * b[j] % a[i];}
		b[i] = a[i] / gcd(a[i],cnt);
		//cout << b[i] << ' ' << i << endl;
	}
	for (int i = 1;i <= n;i++)
	{ans = b[i] % mod * ans % mod;}
	printf("%d",ans);
	return 0;
} 

其中最后算ans的一行如果换成

ans = ans % mod * b[i] % mod;

就会错，比如说

2
700442971370034452 959019558094624110

原程序输出918734010,换顺序后输出-368504960