import math
n,k = list(map(int, input().split()))
a = list(map(int, input().split()))
s,f = 0,0
for i in range(n-1):
    t1,t2 = a[i]//k,a[i]%k
    if a[i]:
        if t1:
            s+=t1
            if t2:
                a[i+1]+=t2
                f=1
            else:
                f=0
        elif f:
            s+=1
            f=0
        else:
            a[i+1]+=a[i]
            f=1
    else:
        continue
s+=math.ceil(a[-1]/k)
print(s)