import math

# Press the green button in the gutter to run the script.
if __name__ == '__main__':
    bs = input()
    input = input()
    inner = False
    innercount = 0
    totaloppositeneeded = 0
    totalneeded = 0
    red = 0
    blue = 0
    result = 0
    tiles = []
    for char in input:
        tiles.append(char)
        if char == 'X':
            blue +=1
        if char == 'O':
            red +=1

    if red > blue:
        inner = False
        innercount = math.sqrt(blue)

    if blue > red:
        inner = True
        innercount = math.sqrt(red)


    # totaloppositeneeded = innercount*4 +4
    # totalneeded = totaloppositeneeded + innercount



    for k in range(int(innercount), 0, -1):
        j = 0
        totaloppositeneeded = k * 4 + 4
        totalneeded = totaloppositeneeded + k
        for i in range (len(tiles)):
            tempred = 0
            tempblue = 0
            j = i
            while j < len(tiles):
                if tiles[j] == 'X':
                    tempblue +=1
                if tiles[j] == 'O':
                    tempred += 1
                j = j+1
            if (inner == False and k == tempblue and totaloppositeneeded <= tempred):
                result +=1
            if (inner == True and k == tempred and totaloppositeneeded <= tempblue):
                result +=1

    print(result)