#include <queue>
#include <iostream>
#include <vector>
#include <cstring>
#include <iostream>
#include <set>
#include <cstring>
#include <stack>
#include <algorithm>
#include <map>
#include <cmath>
//#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn = 1e6 + 10;
const ll INF = 3e16 + 10;
const int max_point = 10000000;
int segment_tree[3 * maxn];
void build_tree(int L, int R, int node) {
    if(L == R) {
        segment_tree[node] = 0;
    }
    else {
        int mid = (L + R) / 2;
        build_tree(L, mid, 2 * node);
        build_tree(mid + 1, R, 2 * node + 1);
        segment_tree[node] = segment_tree[2 * node] + segment_tree[2 * node + 1];
    }
}
void update(int L, int R, int node, int idx, int new_value) {
    if(L == R) {
        segment_tree[node] = new_value;
        return;
    }
    int mid = (L + R) / 2;
    if(idx <= mid) {
        update(L, mid, 2 * node, idx, new_value);
    }
    else {
        update(mid + 1, R, 2 * node + 1, idx, new_value);
    }
    segment_tree[node] = segment_tree[2 * node] + segment_tree[2 * node + 1];
}
int query(int L, int R, int node, int i, int j) {
    // L R i L R j L R
    if(i <= L and R <= j) {
        return segment_tree[node];
    }
    if(R < i or j < L) {
        return 0;
    }
    int mid = (L + R) / 2;
    return query(L, mid, 2 * node, i, j) + query(mid + 1, R, 2 * node + 1, i, j);
}
int main() {
    ios_base::sync_with_stdio(false);
    int n;
    cin >> n;
    build_tree(0, n, 1);
    vector<int> v(n);
    for(int i = 0; i < n; i++) {
        cin >> v[i];
    }

    ll res = 0;
    for(int i = n - 1; i >= 0; i--) {
        update(0, n, 1, v[i], 1);
        res += query(0, n, 1, 0, v[i] - 1);
    }
    cout << res << endl;
    return 0;
}