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)]
P=[0]*(N+1)
LA=0

for fl in range(2):
    ANS=[float("inf")]*(N+1)
    Q=[start]
    ANS[start]=0

    while Q:
        x = heapq.heappop(Q)
        time = x>>20
        fr = x - (time<<20)
        if time > ANS[fr]:
            continue

        for to,cost,vol,ind in EDGE[fr]:
            
            if vol>0 and ANS[to]>ANS[fr]+cost+P[fr]-P[to]:
                
                ANS[to]=ANS[fr]+cost+P[fr]-P[to]
                BACK[to]=[fr,ind]
                heapq.heappush(Q,((ANS[to])<<20)+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

print(LA)