Buggy python submission (verdict: Time Limit Exceeded):
#!/usr/bin/env python3
from collections import defaultdict,deque
from heapq import heappush, heappop
from bisect import bisect_left, bisect_right
import sys, random, itertools, math
sys.setrecursionlimit(10**5)
input = sys.stdin.readline
sqrt = math.sqrt
def LI(): return list(map(int, input().split()))
def LF(): return list(map(float, input().split()))
def LI_(): return list(map(lambda x: int(x)-1, input().split()))
def II(): return int(input())
def IF(): return float(input())
def LS(): return list(map(list, input().split()))
def S(): return list(input().rstrip())
def IR(n): return [II() for _ in range(n)]
def LIR(n): return [LI() for _ in range(n)]
def FR(n): return [IF() for _ in range(n)]
def LFR(n): return [LI() for _ in range(n)]
def LIR_(n): return [LI_() for _ in range(n)]
def SR(n): return [S() for _ in range(n)]
def LSR(n): return [LS() for _ in range(n)]
mod = 1000000007
inf = float('INF')

class BinaryIndexedTree:
    # http://hos.ac/slides/20140319_bit.pdf
    def __init__(self, size):
        """
        :param int size:
        """
        self.bit = [0 for _ in range(size)]
        self.size = size

    def add(self, i, w):
        """
        i番目にwを加える
        :param int i:
        :param int w:
        :return:
        """
        x = i + 1
        while x <= self.size:
            self.bit[x - 1] += w
            x += x & -x
        return

    def sum(self, i):
        """
        [0,i]の合計
        :param int i:
        :return:
        """
        res = 0
        x = i + 1
        while x > 0:
            res += self.bit[x - 1]
            x -= x & -x
        return res

    def search(self, x):
        """
        二分探索。和がx以上となる最小のインデックス(>= 1)を返す
        :param int x:
        :return :
        """
        i = 1
        s = 0
        step = 1 << (self.size.bit_length() - 1)
        while step:
            if i + step <= self.size and s + self.bit[i + step - 1] < x:
                i += step
                s += self.bit[i - 1]
            step >>= 1
        return i

    def __len__(self):
        return self.size
#solve
def solve():
    n, k = LI()
    a = LI_()
    ab = a[::1]
    a[0] = a[0] % k
    for i in range(n - 1):
        a[i + 1] = (a[i] + a[i + 1]) % k
    Bit = BinaryIndexedTree(k + 1)
    ans = 0
    d = deque([0])
    Bit.add(0, 1)
    for x, i in enumerate(a):
        d.append(i)
        if len(d) == k+1:
            x = d.popleft()
            Bit.add(x, -1)
        ans += Bit.sum(i) - Bit.sum(i - 1)
        Bit.add(i, 1)
    print(ans)
    return


#main
if __name__ == '__main__':
    solve()

Fixed submission:
#!/usr/bin/env python3
from collections import defaultdict,deque
from heapq import heappush, heappop
from bisect import bisect_left, bisect_right
import sys, random, itertools, math
sys.setrecursionlimit(10**5)
input = sys.stdin.readline
sqrt = math.sqrt
def LI(): return list(map(int, input().split()))
def LF(): return list(map(float, input().split()))
def LI_(): return list(map(lambda x: int(x)-1, input().split()))
def II(): return int(input())
def IF(): return float(input())
def LS(): return list(map(list, input().split()))
def S(): return list(input().rstrip())
def IR(n): return [II() for _ in range(n)]
def LIR(n): return [LI() for _ in range(n)]
def FR(n): return [IF() for _ in range(n)]
def LFR(n): return [LI() for _ in range(n)]
def LIR_(n): return [LI_() for _ in range(n)]
def SR(n): return [S() for _ in range(n)]
def LSR(n): return [LS() for _ in range(n)]
mod = 1000000007
inf = float('INF')

#solve
def solve():
    n, k = LI()
    a = LI_()
    ab = a[::1]
    a[0] = a[0] % k
    for i in range(n - 1):
        a[i + 1] = (a[i] + a[i + 1]) % k
    ans = 0
    q = deque([0])
    d = defaultdict(int)
    d[0] += 1
    for x, i in enumerate(a):
        q.append(i)
        if len(q) == k+1:
            x = q.popleft()
            d[x] -= 1
        ans += d[i]
        d[i] += 1
    print(ans)
    return


#main
if __name__ == '__main__':
    solve()