for s in[*open(0)][2::2]:
*a,=map(int,s.split());r=1;p=3e9
while a and p:
q=a.pop()
while q>=p:r+=1;q>>=1
p=q
print(r*(a==[])-1)#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define pb push_back
#define forn(i,x,n) for(int i=x; i<n; i++)
void solve() {
ll n;
cin>>n;
ll arr[n];
forn(i,0,n) cin>>arr[i];
int cnt = 0;
for(int i=n-1; i>0; i--){
if(arr[i-1] >= arr[i]){
if(arr[i] == 0){
cout<<"-1\n";
return;
}
while(arr[i-1] >= arr[i]){
arr[i-1] /= 2;
cnt++;
}
}
}
cout<<cnt<<"\n";
}
int main(){
int t;
cin>>t;
while(t--){
solve();
}
}
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