658 B | 658 chars
import sys
from math import sqrt, pi, sin, factorial, ceil, floor
from datetime import datetime, timedelta
# sys.setrecursionlimit(10**7)
BLANK = " "
# inp = input
inp = lambda : sys.stdin.readline().rstrip()
mii = lambda x = BLANK : [*map(int,inp().split(x))]
mfi = lambda x = BLANK : [*map(float,inp().split(x))]
ii = lambda : int(inp())
fi = lambda : float(inp())
p = print
def solve():
n = ii()
s = inp()
i = 0
ans = 0
while i < n:
if i + 1 < n:
if s[i] != s[i + 1]:
ans += 1
i += 2
continue
i += 1
p(ans)
if __name__ == "__main__":
tc = 1
for t in range(1, tc+1):
ret = solve()