#include<bits/stdc++.h>
using namespace std;
#define rep(i,s,t) for(int i=s;i<=t;++i)
#define per(i,s,t) for(int i=s;i>t;--i)
#define dd(x) cout<<#x<<" = "<<x<<" "
#define de(x) cout<<#x<<" = "<<x<<"\n"
#define sz(x) x.size()
#define pb push_back
#define lson k<<1,l,mid
#define rson k<<1|1,mid+1,r
#define mp make_pair
#define fi first
#define se second
typedef long long ll;
typedef double db;
typedef pair<int,int> pii;
const int N=4e5+11;
const int mod=998244353;
ll a[N],b[N];
ll T,n,k,ans;
ll m,x,y;
int main(){
    scanf("%lld",&T);
    while(T--){
        scanf("%lld%lld",&n,&m);
        ll sum=0,mx=0;
        rep(i,1,n){
            scanf("%lld",a+i);
            sum+=a[i];
            mx=max(mx,sum);
        }
        x=0;ans=0;
        ++ans;
        rep(i,1,n){
            x+=a[i];
            if(x<0)x=0;
            if(x>=m){
                printf("%d\n",ans);
                goto end;
            }
        }
        y=x;
        ++ans;
        rep(i,1,n){
            x+=a[i];
            if(x<0)x=0;
            if(x>=m){
                printf("%d\n",ans);
                goto end;
            }
        }
        if(x<=y){
            puts("-1");
        }
        else{
            ll p=(m-mx-x+x-y-1)/(x-y);
            printf("%lld\n",ans+1+p);
        }
        end:;
    }
    return 0;
}