#include <bits/stdc++.h>
using namespace std;
const int MAXN = 500100;
long long tree[MAXN],ranks[MAXN];
long long ans,n;
struct point {
    long long num,val;
} a[MAXN];
bool cmp(point q,point w) {
    if(q.val == w.val) return q.num < w.num;
    return q.val < w.val;
}
void add(int p,long d) {
    for(; p<=n; p += p & (-p)) tree[p] += d;
}
long long sum(int p) {
    long long pll = 0;
    for(; p; p -= p & (-p)) pll += tree[p];
    return pll;
}
int main() {
    scanf("%lld\n",&n);
    for(int i=1; i<=n; i++){
        scanf("%lld\n",&a[i].val);
        a[i].num = i;
    }
    sort(a+1,a+1+n,cmp);
    for(int i=1; i<=n; i++) ranks[a[i].num] = i;
    for(int i=n; i>=1; i--) {
        ans += sum(ranks[i] - 1);
        add(ranks[i],1);
    }
    printf("%lld\n",ans);
    return 0;
}