A_Guess_the_Maximum.py

import sys,math,os
from collections import defaultdict, deque, Counter, OrderedDict, namedtuple
from bisect import bisect_right, bisect_left

def li(): return list(map(int, sys.stdin.readline().strip().split()))
def intp(): return int(sys.stdin.readline().strip())

def string():
    return sys.stdin.readline().strip()

def fast_io():
    sys.stdin = open(0)
    sys.stdout = open(1, "w")

def solve():
    # Start here
    n = intp()
    arr = li()
    ans = float("inf")
    for i in range(len(arr)-1):
        x = arr[i]
        y = arr[i+1]
        val = max(x,y)
        ans = min(ans,val-1)
    print(ans)
    return

if __name__ == "__main__":
    fast_io()
    t = int(input())
    for _ in range(t):
        solve()