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// ~/.vim/cpp_template.cpp
#include <bits/stdc++.h>
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>

#define REP(i,a,b) for (int i = a; i < b; i++)

// Type Aliases for 1D and 2D vectors with initialization
#define vi(n, val) vector<int>(n, val) // 1D vector of ints with size n, initialized to val
#define vll(n, val) vector<long long>(n, val) // 1D vector of long longs with size n, initialized to val
#define ll long long
#define vvi(n, m, val) vector<vector<int>>(n, vector<int>(m, val)) // 2D vector of ints (n x m), initialized to val
#define vvll(n, m, val) vector<vector<long long>>(n, vector<long long>(m, val)) // 2D vector of long longs (n x m), initialized to val


using namespace std;

template <typename T>
void pV(const std::vector<T>& vec, const std::string& label = "Vector") {
    std::cout << label << ": [ ";
    for (const auto& elem : vec) {
        std::cout << elem << " ";
    }
    std::cout << "]" << std::endl;
}


using namespace std;


void dfs(int s, vector<bool> *visited, vector<int> (*adj)[]) {
    if ((*visited)[s]) return;
    (*visited)[s] = true;
    // process node s


    for (auto u: (*adj)[s]) {
        dfs(u, visited, adj);
    }
}
/*
vector<int> adj[N];                                                          
vector<bool> visited(N, false);
int u, v;
for(int i = 0; i < M;i++){
    cin >> u >> v;
    u--;
    v--;
    adj[u].push_back(v);
    adj[v].push_back(u);
}
*/

long long countMerge(vector<int>& vals, int l, int m, int r){
    int x = m-l+1, y = r-m;

    vector<int> left(x,0), right(y, 0);
    REP(i, 0, x){
        left[i] = vals[i+l];
    }
    REP(i, 0, y){
        right[i] = vals[1 + m + i];
    }

    long long res = 0;
    int i = 0, j= 0, k =l;
    while(i < x && j < y){
        if(left[i] <= right[j]){
            vals[k++] = left[i++];
        }else{
            vals[k++] = right[j++];
            res += (x - i);
        }
    }

    while(i < x){
        vals[k++] = left[i++];
    }
    while(j < y){
        vals[k++] = right[j++];
    }
    return res;
}

long long countInversions(vector<int>& vals, int l, int r){
    long long res = 0;
    if(l < r) {
        int m = (r+l) /2;

        res += countInversions(vals, l, m);
        res += countInversions(vals, m+1, r);

        res += countMerge(vals, l, m, r);
    }
    return res;
}

int main() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    // Your code starts here
    int n;
        cin >> n;

    vector<int> vals(n, 0);
    REP(i, 0, n){
        cin >> vals[i];
    }

    cout << countInversions(vals, 0, n-1) << endl;
    return 0;
}

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