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

if n == 0:
    print(0)
    exit()

# Count the number of color changes when moving from right to left
count = 1
prev = s[-1]
for i in range(n-2, -1, -1):
    if s[i] != prev:
        count += 1
        prev = s[i]

# Count the number of times a color is the same as two positions to the right
d = 0
for i in range(n-3, -1, -1):
    if s[i] == s[i+2]:
        d += 1

print(count - d)