// #pragma comment(linker, "/STACK:1024000000,1024000000")

#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <cmath>
#include <algorithm>
#include <iostream>
#include <queue>
#include <stack>
#include <map>
#include <set>
#include <vector>

using namespace std;

#define rep(i, l, r) for(int i=l; i<=r; i++)
#define dow(i, l, r) for(int i=l; i>=r; i--)
#define fi first
#define se second
#define pb push_back
#define mp make_pair
#define clr(x, c) memset(x,c,sizeof(x))

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int,int> Pii;

inline int read() {
    int x=0,f=0; char ch=getchar();
    while (ch<'0' || '9'<ch) f|=ch=='-', ch=getchar();
    while ('0'<=ch && ch<='9') x=x*10+ch-'0', ch=getchar();
    return f?-x:x;
}

// ====================================================== 全局数据

// #define Q 1000000007

// ====================================================== 模板代码

// =========================== 加边

// #define travel(x) for(edge *p=fir[x]; p; p=p->n)
// struct edge{int y; edge *n;} e[maxm], *fir[maxn], *pt=e;
// void AddE(int x, int y){pt->y=y, pt->n=fir[x], fir[x]=pt++;}

// =========================== 快速幂

// inline int pow(int x, int t) {
//     int g = 1;
//     while (t) {
//         if (t&1) g = 1LL*g*x%Q;
//         x = 1LL*x*x%Q;
//         t >>= 1;
//     }
//     return g;
// }

// ====================================================== 主程序

#define maxn 100000

int a[maxn];
int n; ll m;

int main() {
    int T = read(); while (T--) {
        scanf("%d%lld", &n, &m);
        rep(i, 1, n) a[i] = read();
        ll x = 0, y = 0, mn = 0, mx = 0, ans = 0, st = m;
        rep(i, 1, n) {
            x += a[i], y += a[i];
            if (y < mn) mn = y;
            if (y > mx) mx = y;
            if (x < 0) x = 0;
            if (x >= m) {ans = 1; break;}
            if (m - x - mn < st) st = m - x - mn;
        }
        if (ans) {puts("1"); continue;}
        if (st <= x) {puts("2"); continue;}
        if (mn < 0) {
            if (x + mn <= 0) {puts("-1"); continue;}
        }
        if (y < 0) {puts("-1"); continue;}
        ans = 2;
        ans += (st-x) / y; x += (st-x)/y*y;
        while (x < st) x += y, ans += 1;
        printf("%lld\n", ans);
    }
    return 0;
}