#include <iostream>
#include <algorithm>
#include <cstring>

using namespace std;

const int N=100010;

typedef long long ll;
int q[N];
int tmp[N];

ll  merge_sort_count(int q[],int l,int r){

    if(l>=r) return 0;

    int mid = l+r >> 1;
    ll s;
    s = merge_sort_count(q,l,mid)+merge_sort_count(q,mid+1,r);

    int k=0;
    int i=l,j=mid+1;
    while(i<=mid && j<=r){
        if(q[i]<=q[j]) tmp[k++]=q[i++];
        else {
            tmp[k++]=q[j++];
            s += mid-i+1;
        }
    }
    while(i<=mid) tmp[k++]=q[i++];
    while(j<=r) tmp[k++]=q[j++];

    for(int i=l,j=0;i<=r;i++,j++) q[i]=tmp[j];

    return s;
}

int main(){
    int n;
    scanf("%d",&n);
    for(int i=0;i<n;i++) scanf("%d",&q[i]);

    cout<<merge_sort_count(q,0,n-1)<<endl;
    return 0;
}