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

int main(){
    int N; cin >> N;
    vector<int> A(N);
    for(int &x: A)cin >> x;
    ll cnt = 0, l = 0;
    for(int r = 0; r < N; r++){
        while(A[r] == 1){
            r++;
        }
        cnt += (ll)(N - r) * (ll)(r - l + 1);
        l = r + 1;
    }
    cout << cnt << endl;
}