#include <iostream>
#include <random>
using namespace std;
#define MaxSize 100010
typedef long long ElemType;
ElemType sum = 0;

ElemType B[MaxSize];
void Merge(ElemType A[], int low, int mid, int high){
    int tempSum = 0;
    for(int i = low;i <= high;i ++)
        B[i] = A[i];        // A先往B复制
    int i = low, j = mid + 1;
    int k = low;
    while(i <= mid && j <= high){
        if(B[i] <= B[j])        A[k ++] = B[i ++];
        else{
            sum += (mid - i + 1);       // 由已得的排列知有这么多个在j之前且>B[j]的元素
            A[k ++] = B[j ++];
        }
    }
    while(i <= mid)     A[k ++] = B[i ++];
    while(j <= high)    A[k ++] = B[j ++];

}

void MergeSort(ElemType a[], int low, int high){
    if(low < high){
        int mid = (low + high) / 2;
        MergeSort(a, low, mid);
        MergeSort(a, mid + 1, high);
        Merge(a, low, mid, high);
    }
}

int main(){
    ElemType arr[MaxSize];
    int n;
    cin >> n;
    for(int i = 0;i < n;i ++)        cin >> arr[i];
    MergeSort(arr, 0, n - 1);
    cout << sum << endl;
    return 0;
}