def workbook(n, k, arr):
    m=1
    n=1
    o=0
    acc=0
    while (o != len(arr)):
        le = min(m+k-1, arr[o])
        if (m <= n and n <= le):
            acc+=1
        m = le + 1
        if (m > arr[o]):
            o+=1
            m=1
        n+=1
    return acc