c 为啥只对6个点

#include<iostream>
#include<cstdio>
using namespace std;
int a[500005] , temp[500005] , n;
long long ans = 0;
void Merge(int left, int mid, int right)
{
    int i = left, j = mid + 1, k = 0;
    while ((i <= mid) && (j <= right))
    {
        if (a[i] < a[j])temp[k++] = a[i++];
        else
        {
            temp[k++] = a[j++];
            ans += mid - i + 1;
        }
    }
    while (i <= mid)
    {
        temp[k++] = a[i++];
    }
    while (j <= right)temp[k++] = a[j++];
}
void MergeSort(int left, int right)
{
    int mid, i, k;
    if (left < right)
    {
        mid = (left + right) / 2;
        MergeSort(left, mid);
        MergeSort(mid + 1, right);
        Merge(left, mid, right);k = 0;
        for (i = left;i <= right;i++)a[i] = temp[k++];
    }
}
inline int read() {//快读
    char ch = getchar();
    int x = 0, f = 1;
    while (ch<'0' || ch>'9') { if (ch == '-') f = -1;ch = getchar(); }
    while (ch >= '0'&&ch <= '9') x = x * 10 + (ch ^ 48), ch = getchar();
    return x * f;
}
int main()
{
    int i;
    cin >> n;
    for (i = 0;i < n;i++) a[i] = read();;
    MergeSort(0, n - 1);
    cout << ans << endl;
    system("pause");
    return 0;
}