#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define mp make_pair
#define ALL(x) (x).begin(),(x).end()
#define rALL(x) (x).rbegin(),(x).rend()
#define srt(x) sort(ALL(x))
#define rev(x) reverse(ALL(x))
#define rsrt(x) sort(rALL(x))
#define sz(x) (int)(x.size())
void die(string S){puts(S.c_str());exit(0);}
ll delta[100100];
int n;
ll m;
ll run(ll x,bool EXIT)
{
    for(int i=0;i<n;i++)
    {
        x+=delta[i];
        if(x>=m)
            return m;
        x=max(x,0ll);
    }
    return x;
}
void solve()
{
    ll a=0,b=0;
    scanf("%d%lld",&n,&m);
    for(int i=0;i<n;i++)
    {
        scanf("%lld",delta+i);
        a+=delta[i];
        b=max(a,b);
    }
    ll Delta=run(0,0);
    if(!Delta)
    {
        puts("-1");
        return ;
    }
    if(Delta>=m)
    {
        cout<<1<<endl;
        return ;
    }
    ll l=0,r=m;
    while(l<r)
    {
        ll mid=(l+r)/2;
        ll SOL=run(mid,0);
        if((SOL<m&&SOL-mid==Delta))
            l=mid+1;
        else    r=mid;
    }
    assert(l);
    ll ans=(l+Delta-1)/Delta;
    ll cur=ans*Delta;
    if(cur>=m)
    {
        cout<<(m-b+Delta-1)/Delta+1<<endl;
        return ;
    }
    Delta=run(cur,0)-cur;
    if(!Delta)
    {
        puts("-1");
        return ;
    }
    cout<<ans+max(1ll,(m-b-cur+Delta-1)/Delta+1)<<endl;
}
int main()
{
    int t;
    scanf("%d",&t);
    while(t--)
        solve();
    return 0;
}