#include <iostream>

using namespace std;

const int N = 100010;
int q[N], temp[N];
typedef long long LL;


LL merge_sort(int l, int r){
    if(l >= r) return 0;

    int mid = l + r >> 1;
    LL result = merge_sort(l, mid) + merge_sort(mid + 1, r);

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

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

    return result;
}

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

    cout << merge_sort(0, n - 1) << endl;

    return 0;

}