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

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

# Split into runs
runs = []
current = s[0]
runs.append(current)
for c in s[1:]:
    if c != current:
        current = c
        runs.append(current)

m = len(runs)
k = 0

for i in range(2, m):
    if runs[i] == runs[i-2] and runs[i-1] != runs[i]:
        k += 1

print(m - k)