#include <iostream>

using namespace std;

int main() {
    int n;
    int result= 0;
    int check = 1;
    int arr[101]={0,};
    int m;
    
    scanf("%d",&n);
    for(int i =0;i<n;i++){
        scanf("%d",&m);
        arr[i]=m;
        //printf("%d", m);
    }
    for(int i=0;i<n;i++){
        if ( arr[i] == 0){
            check = 1;
        }
        else{
            result +=check;
            check +=1;
        
        }
    }

    printf("%d",result);
    return 0;
}