from heapq import *

n, m = map(int, input().split())
C = [0] * m
D = [0] * m
edges = [[] for _ in range(n)]

for i in range(m):
    u, v, C[i], D[i] = map(int, input().split())
    u -= 1
    v -= 1
    edges[u].append((v, i))
    edges[v].append((u, i))

def dijkstra():
    dist = [1 << 60] * n
    dist[0] = 0
    bV = [-1] * n
    bE = [-1] * n
    hq = [0]
    while hq:
        tmp = heappop(hq)
        d = tmp // n
        pos = tmp - n * d
        if d > dist[pos]:
            continue
        for npos, i in edges[pos]:
            nd = d + C[i]
            if nd < dist[npos]:
                dist[npos] = nd
                bV[npos] = pos
                bE[npos] = i
                heappush(hq, nd * n + npos)
    
    p = n - 1
    while p != 0:
        i = bE[p]
        C[i] = D[i]
        p = bV[p]
    return dist[-1]

ans = dijkstra() + dijkstra()
print(ans)