#include <algorithm>
#include <cstdio>
#include <cstring>
#include <iostream>
#include <vector>
#define setIO(x) freopen(x".in", "r", stdin), freopen(x".out", "w", stdout)
#define closefile fclose(stdin), fclose(stdout)
#define m_p make_pair
#define sz(x) (int)x.size()
#define see(x) cerr << x << " "
#define seeln(x) cerr << x << endl
#define out(x) cerr << #x << " = " << x << " "
#define outln(x) cerr << #x << " = " << x << endl
#define outarr(x, l, r) {cerr << #x"[" << l << " ~ " << r << "] = "; for (int _i = l; _i <= r; ++_i) cerr << x[_i] << " "; cerr << endl;}
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
template <class T> bool checkmax(T &a, T b){return a < b ? a = b, 1 : 0;}
template <class T> bool checkmin(T &a, T b){return b < a ? a = b, 1 : 0;}
const int N = 100005;
const ll inf = 0x3f3f3f3f3f3f3f3f;
int n;
ll m;
ll a[N];
struct node
{
    ll a, b;
    node(ll a = 0, ll b = 0):a(a), b(b){}
}c[N], p[77];
node operator + (node a, node b)
{
    //out(a.a); outln(b.a);
    node c = node(a.a + b.a, max(a.b + b.a, b.b));
    if (c.a > inf) c.a = inf;
    if (c.b > inf) c.b = inf;
    if (c.a < -inf) c.a = -inf;
    if (c.b < -inf) c.b = -inf;
    return c;
}

bool check(ll rnd)
{
    ll x = rnd - 1;
    node t(0, 0);
    for (int i = 60; i >= 0; --i) if (x >> i & 1) t = t + p[i];
    if (max(t.a, t.b) >= m) return 1;
    for (int i = 1; i <= n; ++i)
    {
        t = t + c[i];
        if (max(t.a, t.b) >= m) return 1;
    }
    return 0;
}

void init()
{
    scanf("%d%lld", &n, &m);
    for (int i = 1; i <= n; ++i) scanf("%lld", &a[i]);
    for (int i = 1; i <= n; ++i) c[i] = node(a[i], 0);
}

void solve()
{
    node t(0, 0);
    for (int i = 1; i <= n; ++i) t = t + c[i];
    if (max(t.a, t.b) <= 0)
    {
        printf("-1\n");
        return;
    }
    p[0] = t;
    for (int i = 1; i <= 60; ++i) p[i] = p[i - 1] + p[i - 1];
    ll l = 1, r = 2000000000000000000, mid, best = -1;
    while (l <= r)
    {
        mid = (l + r) >> 1;
        if (check(mid)) best = mid, r = mid - 1;
        else l = mid + 1;
    }
    printf("%lld\n", best);
}

int main()
{
    int t; scanf("%d", &t); while (t--)
    {
        init();
        solve();
    }
    return 0;
}