Codeforces Round #633 (Div. 2) C. Powered Addition

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const int maxn=1e5+10;
ll a[maxn],ans[maxn];
void solve()
{
    int n;
    scanf("%d",&n);
    for(int i=1; i<=n; i++) scanf("%lld",&a[i]);
    ll ma=a[1],maxx=0;
    for(int i=2; i<=n; i++)
    {
        if(a[i]<ma)
          maxx=max(maxx,ma-a[i]);
        else if(a[i]>=ma)
            ma=a[i];
    }
    if(maxx==0)
     printf("0\n");
    else
    {
        int cnt=0;
        while(maxx)
        {
            maxx/=2;
            cnt++;
        }
        printf("%d\n",cnt);
    }
    
}
int main()
{
    int t;
    cin>>t;
    while(t--) solve();
    //system("pause");
    return 0;
}