n = int(input())
s = input().strip()

if n == 0:
    print(0)
else:
    blocks = []
    prev = s[0]
    blocks.append(prev)
    for c in s[1:]:
        if c != prev:
            blocks.append(c)
            prev = c
    k = len(blocks)
    if k == 0:
        print(0)
    else:
        first_color = blocks[0]
        c_count = 0
        for color in blocks[1:]:
            if color == first_color:
                c_count += 1
        print(k - c_count)