#include <bits/stdc++.h>
using namespace std;
int main() {
// your code goes here
int t,i,n,k;
cin>>t;
while(t--){
cin>>n>>k;
int ar[n];
int sum=0;
for(i=0;i<n;i++){
cin>>ar[i];
sum+=ar[i];
}
if(sum<k){
cout<<-1<<endl;
}
else if(sum==k&&n==1){
cout<<n<<endl;
}
else{
vector<int>pre;
int ans=0;
pre.push_back(ar[0]);
for(i=1;i<n;i++){
pre.push_back(pre[i-1]+ar[i]);
//cout<<pre[i-1];
if(pre[i]>=k){
int rem=pre[i]-k;
if(rem==0){
ans=max(ans,i+1);
}
else{
int indx=lower_bound(pre.begin(),pre.end(),rem)-pre.begin();
ans=max(ans,i-indx);
}
}
}
cout<<n-ans<<endl;
}
}
return 0;
}
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