#include<bits/stdc++.h>
using namespace std;
bool x[100001]={0};
int main()
{
	int n;
	cin>>n;
	bool j=0;
	int l,r;
	for(int i=1;i<=n;i++){
		bool p;
		cin>>p;
		if(p)x[i]=1;
		if(!j&&!p)l=i;
		if(p){
			j=1;
			if(j)r=i;
		}
	}
	if(!j)cout<<"0"<<endl;
	else cout<<r-l<<endl;
	return 0;
}