能问一下这个代码为什么会UKE

#include<bits/stdc++.h>
using namespace std;
#define re register
#define ll long long
const int N=3e5+10; 
inline ll read(){
	ll f=0,fu=1;char c=getchar();
	while(c<'0'||c>'9'){if(c=='-')fu=-1;c=getchar();}
	while(c>='0'&&c<='9'){f=(f<<3)+(f<<1)+c-48;c=getchar();}
	return f*fu;
}
inline void write(ll x){
	if(x<0)x=-x,putchar('-');
	if(x>9)write(x/10);
	putchar(x%10+'0');
}
ll n,a[N],ans;
int main(){
	n=read();a[1]=read();
	for(int i=2;i<=n;i++){
		a[i]=read();
		a[i+1]=1e8;
		ans+=lower_bound(a+1,a+i+1,a[i])-a-1;
	}
	write(ans);puts("");
	return 0;
}