could_give_to_one_brigada = int(input())
number_classes = int(input())
classes = []
for i in range(number_classes):
    classes.append(int(input()))
k = len(classes)
a = []
for i in range(k - 1, -1, -1):
    a.append(classes[i])
k = a[0]
while k == 0:
    a.remove(0)
    if len(a) == 0:
        break
k = 0
if len(a) % could_give_to_one_brigada != 0:
    k = 1
print(len(a) // could_give_to_one_brigada + k)