n = int(input())
stol = list(input())
cnt = 0
flag = True
while len(stol) != 0:
    if flag:
        if stol[0] == 'm' and stol[-1] == 'c':
            stol.pop()
            stol.pop(0)
        elif stol[0] == 'm' or stol[-1] == 'c':
            if stol[0] == 'm':
                stol.pop(0)
            else:
                stol.pop()
        else:
            flag = False
            cnt +=1
    else:
        if stol[0] == 'c' and stol[-1] == 'm':
            stol.pop()
            stol.pop(0)
        elif stol[0] == 'c' or stol[-1] == 'm':
            if stol[0] == 'c':
                stol.pop(0)
            else:
                stol.pop()
        else:
            flag = True
            cnt += 1
print(cnt)