#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
     int N;
    int lv=0;
    bool val;
    int count=0;
    char ch;
    while(--N)
        {
        cin>>N;
        if(ch=='u')
            lv++;
        else
            lv--;
        if(lv<0)
            val=true;
        else
            val=false;
        if(lv==-1 && ch=='d' && val)
            count++;
    }
    cout<<count;
}