蒟蒻问一下各位dalao样例能过为啥只有30(已开longlong)

#include<cstdio>
#include<iostream>
#include<cstring>
#include<string>
#include<algorithm>
#include<cmath>
#include<vector>
#include<queue>
#include<map>
#include<stack>
#include<set>
using namespace std;
typedef long long ll;

#define maxn 500005
int a[maxn], t[maxn], n;
ll ans;

void mergeSort(int l, int r) {
    if(l == r) return;
    int mid = (l+r) / 2;
    mergeSort(l, mid);
    mergeSort(mid+1, r);
    int p = l, q = mid+1, i = l;
    while(p <= mid && q <= r) {
        if(a[p] < a[q]) t[i++] = a[p++];
        else {
            ans += mid-p+1;
            t[i++] = a[q++];
        }
    }
    while(p <= mid) t[i++] = a[p++];
    while(q <= r)   t[i++] = a[q++];
    for(int i = l; i <= r; i++) a[i] = t[i];
}

void inp(void) {
    scanf("%d", &n);
    for(int i = 1; i <= n; i++) scanf("%d", &a[i]);
}

int main() {
    inp();
    mergeSort(1, n);
    cout << ans;
    return 0;
}