50分。。。有些ac有些wa有些tle。。。求助各位大佬，谢谢

#include<iostream>
#include<cmath>
using namespace std;
bool isprime(int x)
{
    int s = sqrt(double(x));
    for (int i = 2;i <= s;i++)
    {
        if (x % i == 0)
            return false;
    }
    return true;
}
int main()
{
    int n,count=0;
    cin >> n;
    int a[10000];
    int min=99999, minx=0,miny=0,minz=0;
    for (int i = 2; i <= n;i++)
    {
        if (isprime(i))
        {
            a[count] = i;
            count++;
        }
    }
    for (int i = 0;i <= count;i++)
    {
        for (int j = i;j <= count;j++)
        {
            for (int k = j;k <= count;k++)
            {
                if (a[i] + a[j] + a[k] == n)
                {
                    if (a[i] < min)
                    {
                        min = a[i];
                        minx = a[i];
                        miny = a[j];
                        minz = a[k];
                    }
                }
            }
        }
    }
    cout << minx << " " << miny << " " << minz;
}