#include <stdio.h>

#include <bits/stdc++.h>

using namespace std;

#define INF 0x3f3f3f3f

#define LC(x) (x<<1)

#define RC(x) ((x<<1)+1)

#define MID(x,y) ((x+y)>>1)

#define CLR(arr,val) memset(arr,val,sizeof(arr))

#define FAST_IO ios::sync_with_stdio(false);cin.tie(0);

typedef pair<int, int> pii;

typedef long long LL;

const double PI = acos(-1.0);

const int N = 500010;

LL arr[N];

LL Max[N][20];

LL prefix[N];

void init()

{

    CLR(Max, -0x3f3f3f3f3f3f3f3f);

    prefix[0] = 0LL;

}

void RMQ_init(int l, int r)

{

    int i, j;

    for (i = l; i <= r; ++i)

        Max[i][0] = max<LL>(Max[i][0], prefix[i]);

    for (j = 1; l + (1 << j) - 1 <= r; ++j)

    {

        for (i = l; i + (1 << j) - 1 <= r; ++i)

        {

            Max[i][j] = max<LL>(Max[i][j - 1], Max[i + (1 << (j - 1))][j - 1]);

        }

    }

}

LL ST(int l, int r)

{

    int k = log2(r - l + 1);

    return max<LL>(Max[l][k], Max[r - (1 << k) + 1][k]);

}

int main(void)

{

    int tcase, n, i;

    LL k;

    scanf("%d", &tcase);

    while (tcase--)

    {

        init();

        scanf("%d%lld", &n, &k);

        for (i = 1; i <= n; ++i)

        {

            scanf("%lld", &arr[i]);

            prefix[i] = prefix[i - 1] + arr[i];

        }

        RMQ_init(1, n);

        int ans = INF;

        for (i = 1; i <= n; ++i)

        {

            int L = i, R = n;

            int temp = -1;

            while (L <= R)

            {

                int mid = (L + R) >> 1;

                LL Get = ST(i, mid);

                if (Get - prefix[i - 1] >= k)

                {

                    temp = mid;

                    R = mid - 1;

                }

                else

                    L = mid + 1;

            }

            if (~temp)

                ans = min(ans, temp - i + 1);

        }

        printf("%d\n", ans == INF ? -1 : ans);

    }

    return 0;

}