def a(x1,y1,x2,y2,xp,yp)
    (x2-x1)*(yp-y1) - (y2-y1)*(xp-x1)
end
def in?(x1,y1,x2,y2,x3,y3,xp,yp)
    res = true
    res &= a(x1,y1,x2,y2,xp,yp) * a(x1,y1,x2,y2,x3,y3) > 0
    res &= a(x1,y1,x3,y3,xp,yp) * a(x1,y1,x3,y3,x2,y2) > 0
    res &= a(x3,y3,x2,y2,xp,yp) * a(x3,y3,x2,y2,x1,y1) > 0
    res
end

until (n = gets.chomp.to_i) == 0
    p = []
    n.times do
        p << gets.chomp.split(',').map(&:to_f)
    end

    min,max =  p.minmax{|a,b| a[0] <=> b[0]}
    array = (p - min - max)
    array.size.times do |i|
        array.size.times do |j|
            next if i==j
            next if array[i]==nil || array[j]==nil
            array[j] = nil if in?(min[0],min[1],max[0],max[1],array[i][0],array[i][1],array[j][0],array[j][1])
        end
    end
    puts array.select{|x| x==nil}.size
end