#include<bits/stdc++.h>
using namespace std;
const int M=2e5+5;

int n;long long m,A[M];
int max0(int x,int y)
{
    if(A[x]>A[y])return x;
    if(A[y]>A[x])return y;
    return x<y?x:y;
}

struct ST_Table
{
    int Max0[M][20];
    int Log[M];
    void Init()
    {
        for(int i=2;i<=2*n;i++)Log[i]=Log[i>>1]+1;
        for(int i=0;i<=2*n;i++)Max0[i][0]=i;
        for(int i=1;(1<<i)<=2*n;i++)
            for(int j=0;j+(1<<i)-1<=2*n;j++)
                Max0[j][i]=max0(Max0[j][i-1],Max0[j+(1<<(i-1))][i-1]);
    }
    int Query(int L,int R)
    {
        int b=Log[R-L+1];
        return max0(Max0[L][b],Max0[R-(1<<b)+1][b]);
    }
}st;

int Stk[M],top,Rb[M];
bool vis[M];
void Solve()
{
    for(int i=1;i<=n;i++)A[n+i]=A[i];
    for(int i=2;i<=2*n;i++)A[i]+=A[i-1];
    for(int i=0;i<=2*n;i++)Rb[i]=-1,vis[i]=false;
    top=0;Stk[++top]=0;
    for(int i=1;i<=2*n;i++)
    {
//        printf("A %d = %lld\n",i,A[i]);
        while(top && A[Stk[top]]>A[i])Rb[Stk[top]]=i,top--;
        Stk[++top]=i;
    }
//    for(int i=0;i<n;i++)printf("Rb %d = %d\n",i,Rb[i]);
    st.Init();
    long long eve=0;int pos=0;
    while(true)
    {
//        printf("pos=%d Rb=%d\n",pos,Rb[pos]);
        if(Rb[pos]!=-1)
        {
            if(vis[pos])return (void)puts("-1");
            vis[pos]=true;
            int p0=st.Query(pos,Rb[pos]);
//            printf("[][][] pos=%d p0=%d\n",pos,p0);
            if(A[p0]>=A[pos]+m)
            {
                eve+=p0-pos;
                return (void)printf("%lld\n",(eve-1)/n+1);
            }
            eve+=Rb[pos]-pos;
            pos=Rb[pos]%n;
        }
        else
        {
            int p0=st.Query(pos,n);
            if(A[p0]>=A[pos]+m)
            {
                eve+=p0-pos;
                return (void)printf("%lld\n",(eve-1)/n+1);
            }
            eve+=n-pos;
            long long nows=A[n]-A[pos],alls=A[n],firs=A[st.Query(0,n)];
            if(alls<=0)return (void)puts("-1");
//            printf("pos=%d eve=%lld nows=%lld alls=%lld firs=%lld\n",pos,eve,nows,alls,firs);
            if(m-firs-nows<=0)return (void)printf("%lld\n",eve/n+1);
            return (void)printf("%lld\n",eve/n+(m-firs-nows-1)/alls+2);
        }
    }
}

int main()
{
    int T;scanf("%d",&T);
    while(T --> 0)
    {
        scanf("%d%lld",&n,&m);
        for(int i=1;i<=n;i++)scanf("%lld",&A[i]);
        Solve();
    }
    return 0;
}