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

int main(){
    int N;
    long sum = 0;
    int length = 0;
    int t;
    scanf("%d",&N);
    for(int i=0;i<N;i++){
        scanf("%d",&t);
        if(t == 1){
            length++;
        } else {
            sum += length*(length+1)/2;
            length = 0;
        }
    }
    sum += length*(length+1)/2;
    printf("%ld",(long)N*((long)N + 1)/2-sum);
}