from heapq import heapify, heappop, heappush
N,M = map(int,input().split()); INF = float("inf")
Graph = [[] for _ in range(N)]
INPUT = []
for i in range(M):
    s,g,x,y = map(int,input().split()); INPUT.append((s,g,x,y))
    s-=1;g-=1
    Graph[s].append((x,g))
    Graph[g].append((x,s))

def dijkstra_heap2(s,G):
  #S:start, V: node, E: Edge, G: Graph
  V = len(G)
  d = [INF for _ in range(V)]
  d[s] = 0
  prev = [0]*V
  prev[s] = -1
  PQ = []
  heappush(PQ,(0,s))
  
  while PQ:
    c,v = heappop(PQ)
    if d[v] < c:
      continue
    d[v] = c
    for cost,u in G[v]:
      if d[u] <= cost + d[v]:
        continue
      d[u] = cost + d[v]
      prev[u] = v
      heappush(PQ,(d[u], u))
  
  return d ,prev

D,PREV = dijkstra_heap2(0,Graph)
#print(D)
ans = D[N-1]
#print(PREV)
now = N-1
Used = set()
while now != 0:
    mae = now
    now = PREV[mae]
    Used.add((mae,now))
Graph.clear()
New_Graph = [[] for _ in range(N)]
for P in INPUT:
    a,b,x,y = P
    a-=1;b-=1
    if (a,b) in Used or (b,a) in Used:
        New_Graph[a].append((y,b))
        New_Graph[b].append((y,a))
    else:
        New_Graph[a].append((x,b))
        New_Graph[b].append((x,a))
#print(New_Graph)
RD, RPREV = dijkstra_heap2(N-1,New_Graph)
#print(RD)
ans += RD[0]
print(ans)