#include<bits/stdc++.h>
using namespace std;
//快读
const int BUFSIZE=1<<30;
char ibuf[BUFSIZE],*is=ibuf,*it=ibuf;
char getc(){
    if(is==it)
        it=(is=ibuf)+fread(ibuf,1,BUFSIZE,stdin);
    return is==it?EOF:*is++;
}
int reads(){
	int ret=0;
	bool sign=0;
	char ch=getc();
	while(!isdigit(ch)){
		sign|=ch=='-';
		ch=getc();
	}
	while(isdigit(ch)){
		ret=ret*10+ch-'0';
		ch=getc();
	}
	return sign?-ret:ret;
}
//正片
int n,a[100005],b[100005],s; 
void merge(int l,int r){
	if(l==r) return;
	int mid=l+(r-l)/2;
	merge(l,mid);
	merge(mid+1,r);
	int i=l,j=mid+1,cnt=l-1;
	while(i<=mid && j<=r){
		if(a[i]>a[j]) s+=mid-i+1,b[++cnt]=a[j++];
		else b[++cnt]=a[i++];
	}
	while(i<=mid) b[++cnt]=a[i++];
	while(j<=r) b[++cnt]=a[j++];
	for(int k=l;k<=r;k++){
		a[k]=b[k];
	}
}
int main(){
	n=reads();
	for(int i=1;i<=n;i++){
		a[i]=reads();
	}
	merge(1,n);
	cout<<s;
}

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