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

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

# Count the number of runs and track the count of each color's runs
runs = 1
current_color = s[0]
color_run_counts = {current_color: 1}

for c in s[1:]:
    if c != current_color:
        runs += 1
        current_color = c
        if current_color in color_run_counts:
            color_run_counts[current_color] += 1
        else:
            color_run_counts[current_color] = 1

# Calculate the number of colors with multiple runs
k = sum(1 for cnt in color_run_counts.values() if cnt >= 2)

# The answer is the number of runs minus k
print(runs - k)