#include <stdio.h>
#include <stdlib.h>
#include <string.h>

int main()
{
    int cnt = 0;
    char c1, c2, c3, c4;
    scanf(" %c %c", &c1, &c2);
    while(scanf(" %c %c", &c3, &c4) != EOF)
    {
        if((c1 == c3 && c2 == c4) || (c1 != c3 && c2 != c4))
            cnt++;
        else if((c1 == c3 && c2 != c4) || (c1 != c3 && c2 == c4))
        {
            c1 = c3;
            c2 = c4;
        }
    }
    printf("%d\n", cnt);
    return 0;
}