import sys
input = sys.stdin.readline
import heapq

N,M=map(int,input().split())

EDGE=[[] for i in range(N+1)]
EDGELIST=[]

eind=0
for i in range(M):
    u,v,c,d=map(int,input().split())
    X=[v,c,1,eind]
    EDGE[u].append(X)
    EDGELIST.append(X)
    eind+=1

    X=[u,c,0,eind]
    EDGE[v].append(X)
    EDGELIST.append(X)
    eind+=1

    X=[u,c,1,eind]
    EDGE[v].append(X)
    EDGELIST.append(X)
    eind+=1

    X=[v,c,0,eind]
    EDGE[u].append(X)
    EDGELIST.append(X)
    eind+=1


    X=[v,d,1,eind]
    EDGE[u].append(X)
    EDGELIST.append(X)
    eind+=1

    X=[u,d,0,eind]
    EDGE[v].append(X)
    EDGELIST.append(X)
    eind+=1

    X=[u,d,1,eind]
    EDGE[v].append(X)
    EDGELIST.append(X)
    eind+=1

    X=[v,d,0,eind]
    EDGE[u].append(X)
    EDGELIST.append(X)
    eind+=1


start=1
goal=N

BACK=[[-1,-1] for i in range(N+1)]
LA=0
P=[0]*(N+1)

for fl in range(2):
    ANS=[float("inf")]*(N+1)
    Q=[(0,start)]
    ANS[start]=0
 
    while Q:
        time,fr = heapq.heappop(Q)
        if time > ANS[fr]:
            continue

        for to,cost,vol,ind in EDGE[fr]:
            
            if vol>0 and ANS[to]>ANS[fr]+cost:
                
                ANS[to]=ANS[fr]+cost
                BACK[to]=[fr,ind]
                heapq.heappush(Q,(ANS[to],to))

    LA+=ANS[goal]+P[goal]
    P=[P[i]-ANS[i] for i in range(N+1)]
 
    NOW=goal
    while NOW!=start:
        fr,ind=BACK[NOW]
        EDGELIST[ind][2]-=1
        EDGELIST[ind^1][2]+=1

        NOW=fr

    for i in range(N+1):
        for j in range(len(EDGE[i])):
            EDGE[i][j][1]+=ANS[EDGE[i][j][0]]-ANS[i]

print(LA)