#include<iostream>
#include<string>
using namespace std;
int main()
{
    int N=0,out=0;
    string ashi1,ashi2;
 
    while(1)
    {
        cin >> N;
        if(N==0) break;
        for(int i=0;i<N/2;i++)
        {
            cin >> ashi1 >> ashi2;
            if((ashi1=="lu"&&ashi2=="ru")||(ashi1=="ru"&&ashi2=="lu")||(ashi1=="ld"&&ashi2=="rd")||(ashi1=="rd"&&ashi2=="ld")) out++;
        }
        if( N%2==1 )cin >> ashi1;
        cout << out << endl;
        out=0;
    }
    return 0;
}