import sys
from collections import deque, Counter
input = lambda: sys.stdin.readline().rstrip()
ii = lambda: int(input())
mi = lambda: map(int, input().split())
li = lambda: list(mi())
inf = 2 ** 63 - 1
mod = 998244353

def Dijkstra(s, graph):
    INF = 2 ** 63 - 1
    import heapq
    n = len(graph)
    dist = [INF] * n
    dist[s] = 0
    bef = [0] * n
    bef[s] = s
    hq = [(0, s)]
    heapq.heapify(hq)
    while hq:
        c, now = heapq.heappop(hq)
        
        if c > dist[now]:
            continue
        for to, cost in graph[now]:
            if dist[now] + cost < dist[to]:
                dist[to] = cost + dist[now]
                bef[to] = now
                heapq.heappush(hq, (dist[to], + to))
    return dist, bef

def DijkstraRest(bef, t):
    now = t
    ret = []
    while bef[now] != now:
        ret.append((bef[now], now))
        now = bef[now]
    ret.reverse()
    return ret

n, m = mi()
edge = [li() for _ in range(m)]
D = {}
for u, v, c, d in edge:
    u -= 1; v -= 1
    D[u, v] = D[v, u] = (c, d)

graph = [[] for _ in range(n)]

for V in D.keys():
    u, v = V
    graph[u].append((v, D[V][0]))
    graph[v].append((u, D[V][0]))

dist, r = Dijkstra(0, graph)

ans = dist[n - 1]

R = set(DijkstraRest(r, n - 1))

graph = [[] for _ in range(n)]

for V in D.keys():
    u, v = V
    if (u, v) in R or (v, u) in R:
        graph[u].append((v, D[V][1]))
        graph[v].append((u, D[V][1]))
    else:
        graph[u].append((v, D[V][0]))
        graph[v].append((u, D[V][0]))

dist, r = Dijkstra(0, graph)

ans += dist[n - 1]

print(ans)