#!/usr/bin/env python
#coding:utf8

def read():
    N = input()
    return map(int, raw_input().split())


def rec(bit, vList):
    if bit == -1:
        return (0, 0)
    
    zeroList = []
    oneList = []
    
    for v in vList:
        if v & (1 << bit):
            oneList.append(v)
        else:
            zeroList.append(v)    

    if zeroList and oneList:
        (x1, val1) = rec(bit - 1, oneList)
        (x2, val2) = rec(bit - 1, zeroList)
        if val1 < val2:
            return (x1             , val1 + (1 << bit))
        else:
            return (x2 + (1 << bit), val2 + (1 << bit))
        
    elif not zeroList and     oneList:
        (x, val) = rec(bit - 1, oneList)
        return (x + (1 << bit), val)
        
    elif     zeroList and not oneList:
        (x, val) = rec(bit - 1, zeroList)
        return (x, val)
    
    else:
        assert False
        

def work(vList):
    (x, val) = rec(32, vList)
    print val


if __name__ == "__main__":
    work(read())