#include <iostream>

using namespace std;

typedef long long LL;

const int N = 100010;
int q[N], tmp[N];

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

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

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

    //扫尾
    while(i <= mid) tmp[k ++] = q[i ++];
    while(j <= r) tmp[k ++] = q[j ++];

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

    return res;

}

int main() {
    int n;
    scanf("%d", &n);

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

    printf("%ld", merge_sort(q, 0, n - 1));

    return 0;

}