#include "bits/stdc++.h"
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define REP(i, n) for(int i = 0; i < (int)(n); i++)
#define REPR(i, n) for(int i = (int)(n); i >= 0; i--)
#define FOR(i,n,m) for(int i = (int)(n); i < int(m); i++)
using namespace std;
typedef long long ll;
const int MOD = 1e9 + 7;
const int INF = MOD - 1;
const ll LLINF = 4e18;

// 0-indexedとして使う
// 実装は1-indexed
template< typename T >
struct BinaryIndexedTree {
    vector< T > data;

    BinaryIndexedTree(int sz) {
        data.assign(++sz, 0);
    }

    // [0,k]
    T sum(int k) {
        T ret = 0;
        for (++k; k > 0; k -= k & -k) ret += data[k];
        return (ret);
    }

    // [left,right]
    T sum(int left, int right) {
        return sum(right) - sum(left - 1);
    }

    void add(int k, T x) {
        for (++k; k < data.size(); k += k & -k) data[k] += x;
    }

    void print() {
        cout << "[ ";
        for (int i = 1; i < data.size(); i++) {
            cout << data[i];
            if (i < data.size() - 1) cout << ", ";
        }
        cout << " ]";
    }
};

int main() {
    int n; cin >> n;
    BinaryIndexedTree< int > bit(n+1);
    vector<int> m(n);
    REP(i, n) {
        cin >> m[i];
    }
    int ans = 0;
    REP(i, n) {
        ans += i - bit.sum(m[i]);
        bit.add(m[i], 1);
    }
    //bit.print();
    cout << ans << endl;
    getchar(); getchar();
}