public class Main {
public static void main(String[] args) {
	Scanner scanner=new Scanner(System.in);
	long N=scanner.nextLong();
	long num=0;
	long pre=-1;
	for(long i=0;i<N;i++){
		long temp=scanner.nextLong();
		if(temp==0){
			num++;
		}
		else if(pre!=-1&&temp==pre){
			num++;
			pre=-1;
		}
		else{
			pre=temp;
		}
	}
	System.out.println(num);
	scanner.close();
}
}
求指导一下