x = int(input())
n = int(input())
a = [int(input()) for i in range(n)]
last = -1
cnt = 0
cnt_rooms = 0
for i in range(n):
    if (a[i] == 1):
        if (last == -1 or cnt_rooms + (i - last) > x):
            cnt += 1
            cnt_rooms = 1
        else:
            cnt_rooms += (i - last)
        last = i
print(cnt)