Powered Addition

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int,int> pi;
 
int T, n;
int INF = 1e9+1;
int ans;
 
// power of most significant 1
int msb(ll x) {
    for (int i = 0; i < 33; i++)
        if (x < (1ll << i))
            return i;
}
 
int main() {
    scanf("%d", &T);
    for (int t = 0; t < T; t++) {
        scanf("%d", &n);
        int ceil = -INF;
        ans = 0;
        for (int i = 0; i < n; i++) {
            int a;
            scanf("%d", &a);
            if (a > ceil) ceil = a;
            else if (ceil != -INF) {
                int d = ceil - a;
                ans = max(ans, msb(d));
            }
        }
        printf("%d\n", ans);
    }
 
    return 0;
}