T = 1
def init():
global T
#T = _I()
def ib(bs, x):
for b in bs:
x = min(x,x^b)
if x:
bs.append(x)
return bs
def minx(bs,x):
for b in sorted(bs,reverse=True):
x = min(x,x^b)
return x
def solve():
N,M = _M()
g = dd(list)
for i in range(M):
a,b,w = _M()
g[a].append((b, w))
g[b].append((a, w))
t = [-1]*(N+1)
t[1] = 0
b = []
vis = [False]*(N+1)
def dfs(u):
vis[u] = True
for v,w in g[u]:
if t[v] == -1:
t[v] = t[u]^w
dfs(v)
else:
if vis[v]:
ib(b,t[u] ^w^ t[v]) #かわいいからスペース
dfs(1)
if t[N] == -1:
print(-1)
else:
print(minx(b,t[N]))
#--------------ごっつりしていってね--------------
#あぁそうそう ごちうさ楽しみ
import sys
import math
from copy import deepcopy as dc
sys.setrecursionlimit(10 ** 6)
from collections import defaultdict as dd
import heapq
from itertools import permutations as per
_S = input;_R = range;_P = print; _E = enumerate;
def _RR(a): return range(a-1,-1,-1)
def _I(): return int(_S())
def _M(): return map(int, _S().split())
def _SS(): return _S().strip().split()
def _L(): return list(_M())
def _LS(): return list(_S())
def _T(): return tuple(_M())
def yn(b): print("Yes" if b else "No")
def fs(b): print("First" if b else "Second")
def lis(c,*a):
if not len(a): return 0 if c == 0 else []
if c == 0: return a[0]
return [lis(c-1,*a[1:]) for i in _R(a[0])]
def in2(a,fn):
for i in _R(len(a)): a[i]=fn()
biga = "ABCDEFGHIJKLMNOPQRSTUVWXYZ";smaa = "abcdefghijklmnopqrstuvwxyz"
ctoi = lambda c: ord(c) - ord('a')
ctoi2 = lambda c: ord(c) - ord('A')
itoc = lambda i: chr(ord('a') + i)
itoc2 = lambda i: chr(ord('A') + i)
inf = 10 ** 18
mod = 998244353
def around(x,y,type_=False):
rt = []
rt.extend([(x+1,y),(x-1,y),(x,y+1),(x,y-1)])
if type_:
rt.extend([(x+1,y+1),(x-1,y-1),(x-1,y+1),(x+1,y-1)])
return rt
def acc(a):
b = [0]
for i in a:
b.append(b[-1] + i)
return b
class heap:
l = []
def __init__(self,*s): self.l = list(s);heapq.heapify(self.l)
def min(self): return False if (len(self.l) == 0) else self.l[0]
def pop(self): return False if (len(self.l) == 0) else heapq.heappop(self.l)
def push(self,n): heapq.heappush(self.l,n)
def dump(self): return heapq.nsmallest(len(self.l),self.l)
def max(self): return False if (len(self.l) == 0) else heapq.nlargest(1,self.l)[0]
def len(self): return len(self.l)
class base:
bn = 0; dig = 0; num = []
def __init__(self,base_num,digit = 0):
self.bn = base_num; self.dig = digit; self.num = [0]*digit
def max(self): return(self.bn**self.dig-1)
def dump(self): return(self.num[::-1])
def ncp(self,digit,n): self.num[digit] = min(self.num[digit]+n,self.bn-1)
def plus(self,digit,n):
for i in _R(digit-self.dig+1): self.num.append(0)
self.dig = max(self.dig,digit+1)
if (self.num[digit]+n >= self.bn):
self.plus(digit+1,(self.num[digit]+n)//self.bn)
self.num[digit] = (self.num[digit]+n)%self.bn
def copy(self,n):
self.num = dc(n)
dig = len(self.num)
def change(self,n):
digit = int(math.log(n,self.bn))if n!=0 else 0+1
for i in _R(digit-self.dig+1): self.num.append(0)
self.dig = max(self.dig,digit+1)
for i in _R(self.dig):
self.num[i] = n%self.bn**(i+1)//self.bn**i
n -= self.num[i]
return self.dump()
def b10(self): return(sum([self.num[i]*self.bn**i for i in _R(self.dig)]))
def gin(N, M=None):
g = [[] for _ in range(N)]
for _ in range(N-1 if M is None else M):
u, v = map(int, input().split());u -= 1;v -= 1
g[u].append(v);g[v].append(u)
return g
def ginh(N, M):
g = [[] for _ in range(N)]
for i in range(M):
u, v, h = map(int, input().split());u -= 1;v -= 1
g[u].append((v,h));g[v].append((u,h))
return g
from atcoder.segtree import SegTree
class rhash:
hs = None
def __init__(self,S,N):
self.hs = SegTree(msum,0,[ctoi(S[i])*pow(31,i,mod) for i in _R(N)])
def get(self,l,r):
return self.hs.prod(l,r+1)*pow(pow(31,l,mod),mod-2,mod)%mod
def getall(self):
return self.hs.all_prod()
def change(self,n,c):
self.hs.set(n,ctoi(c)*pow(31,n,mod))
def nwse(s,x,y,rev=False):
if (rev):
s = {"N":"S","S":"N","W":"E","E":"W"}[s]
if s=="N": return (x-1,y)
elif s=="W": return (x,y-1)
elif s=="S": return (x+1,y)
elif s=="E": return (x,y+1)
init()
for i in _R(T):
solve()