import os, sys
from io import BytesIO, IOBase


def main():
    n, m = rints()
    a, ans = rints(), 0
    for i in range(n - 1, 0, -1):
        rem = m - (a[i] % m)
        
        if rem != m:
            if a[i - 1] >= rem:
                ans += a[i] // m + (rem > 0)
                a[i - 1] -= rem
            else:
                ans += ceil1(a[i] + a[i - 1], m)
                a[i - 1] = 0

    ans += ceil1(a[0], m)
    print(ans)


# FASTIO REGION
class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


BUFSIZE = 8192
sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")
rstr = lambda: input().strip()
rstrs = lambda: [str(x) for x in input().split()]
rstr_2d = lambda n: [rstr() for _ in range(n)]
rint = lambda: int(input())
rints = lambda: [int(x) for x in input().split()]
rint_2d = lambda n: [rint() for _ in range(n)]
rints_2d = lambda n: [rints() for _ in range(n)]
ceil1 = lambda a, b: (a + b - 1) // b
if __name__ == '__main__':
    main()
