#include<bits/stdc++.h>
using namespace std;

#define ll long long
#define mtv(kit) cout<<#kit<<" - "<<kit<<"\n";
#define ff first
#define ss second
#define pb push_back
#define rep(i,a,b) for(i=a;i<b;i++)
#define pii pair<ll , ll>
#define all(x) x.begin(),x.end()
#define nl "\n"
#define ump unordered_map

const ll N = 1e6 + 5;
ll ft[N];

void add(ll in , ll val){
    for(;in <= N; in += in&-in)ft[in] += val;
}

ll query(ll in){
    ll ans = 0;
    for(;in > 0; in -= in&-in)ans += ft[in];
    return ans;
}

void doit(){
    ll n, i, s = 0, x, ans = 0;
    cin >> n;
    rep(i,0,n){
        cin >> x;
        ans += query(x - 1);
        add(x,x);
    }
    cout << ans << nl;
}

int main() {
// #ifndef ONLINE_JUDGE
//     freopen("input1.txt","r",stdin);
//     freopen("output1.txt","w",stdout);
// #endif
//     ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    ll t = 1;
    // cin >> t;
    for(ll i = 1; i <= t; i++){
        doit();
    }
}