def countingValleys(n, s):
    s = list(s)
    level = 0
    points = []
    for i in s:
        if i =='U':
            level += 1
        else:
            level += -1
        points.append(level)
    count = 0
    for i in range(len(points) -1):
        if points[i] < 0 and points[i+1] ==0:
            count +=1
    return count