#include <iostream>
#include <vector>
using namespace std;

int main(){
  int n;cin>>n;
  vector<int> A(n);
  for(int i = 0; n > i; i++){
    cin>>A[i];
  }
  long long nw = 0;
  int nwdex = -1;
  long long ans = 0;
  for(int i = n-1;0 <= i; i--){
    if(nwdex != A[i]){
      nw++;
      nwdex = A[i];
    }else{
      nw = 2;
    }
    if(i != n-1 && A[i] == 1){
      ans += nw-1;
    }
  }
  cout << ans << endl;
}