n, k = input().split(' ')
k, n = int(k), int(n)
r = input().split(' ')
r = list(map(int, r))
ans = n + 1
s = 0
for i in range(0, ans):
    for j in range(i + 1, ans):
        if sum(r[j - i - 1:j]) >= k and len(r[j - i - 1:j]) < ans:
            ans = len(r[j - i - 1:j])
if ans == n + 1:
    ans = -1
print(ans)