#include "bits/stdc++.h"
#include <atcoder/all>
using namespace std;
using namespace atcoder;
using ll = long long;
#define rep(i, n) for (long long int i = 0; i < (long long int)(n); i++)
long long int MOD = 998244353;
int main(){
    ll n;
    cin >> n;
    vector<ll>av;
    rep(i,n){
        ll a;
        cin >> a;
        av.push_back(a);
    }
    reverse(av.begin(),av.end());
    ll ans = 0;
    ll now = 0;
    ll back = av[0];
    for(ll i = 1;i < av.size();i++){
        if(back != av[i]){
            now++;
        }else{
            now = 1;
        }
        back = av[i];
        if(av[i] == 1){
            ans = ans + now;
        }
    }
    cout << ans <<endl;
}