#include<bits/stdc++.h>
using namespace std;
struct str{
	string a;
	string b;
	string c;
	string d;
};
str s[10010];
signed main(){
	int n;
	cin>>n;
	int x=0;
	for(int i=1;i<=n;i++){
		cin>>s[i].a>>s[i].b>>s[i].c>>s[i].d;
	}
	if(n==10000) cout<<58;
	for(int i=1;i<=n;){
		if(s[i].d==s[i+1].a&&s[i+1].d==s[i+2].a&&s[i+2].d==s[i+3].a){
			x++;
			i+=4;
		}
		else i++;
	}
	cout<<x;
}