RT，暴力可过：

#include<bits/stdc++.h>
#define int unsigned long long
using namespace std;
const int maxn=3e4+5;
int n,a[maxn],sum,w1,w2;
signed main(){
	scanf("%llu",&n);
	for(int i=1;i<=n;++i)
		scanf("%llu",&a[i]);
	for(int i=2;i<n;++i){
		w1=w2=0;
		for(int l=1;l<i;++l)
			w1+=(a[l]<a[i]);
		for(int r=i+1;r<=n;++r)
			w2+=(a[r]>a[i]);
		sum+=w1*w2; 
	}
	printf("%llu\n",sum);
	return 0;
}