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

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

changes = 0
for i in range(1, n):
    if s[i] != s[i-1]:
        changes += 1

k = 0
i = 2
while i < n:
    if s[i] == s[i-2] and s[i] != s[i-1]:
        k += 1
        i += 2  # Skip next to avoid overlapping
    else:
        i += 1

print(changes + 1 - k)