// Slower C++ solution:
#include<iostream>

#include<cstdio>

#include<cstdlib>

#include<string>

#include<cstring>

#include<algorithm>

#include<queue>

#include<vector>

#define N 20100

#define M 50010

#define rg register

using namespace std;

typedef long long ll;

typedef double db;

int n,m,tot=0;

int dis[N],head[N],vis[N];

int nxt[M],to[M],w[M],c[M];

void link(int x,int y,int z,int v){

	nxt[tot]=head[x],to[tot]=y,w[tot]=z,c[tot]=v,head[x]=tot++;

}

void spfa(){

	queue <int> q;

	memset(dis,0x3f,sizeof(dis));

	memset(vis,0,sizeof(vis));

	q.push(1),dis[1]=0,vis[1]=1;

	while (!q.empty()){

		int x=q.front();q.pop();

		for (int i=head[x];i!=-1;i=nxt[i]){

			int v=to[i];

			if (dis[v]<=dis[x]+w[i]) continue;

			dis[v]=dis[x]+w[i];

			if (!vis[v]) vis[v]=1,q.push(v);

		}

		vis[x]=0;

	}

}

int main(){

//	freopen ("2249.in","r",stdin);

//	freopen ("2249.out","w",stdout);

	while (scanf ("%d%d",&n,&m)&&(n||m)){

		memset(head,-1,sizeof(head));

		tot=0;int x,y,z,v;

		for (int i=1;i<=m;++i){

			scanf ("%d%d%d%d",&x,&y,&z,&v);

			link(x,y,z,v),link(y,x,z,v);

		}

		spfa();

		int ans=0;

		for (int i=2;i<=n;++i){

			int mx=2000;

			for (int j=head[i];j!=-1;j=nxt[j]){

				v=to[j];

				if (dis[i]==dis[v]+w[j]) mx=min(mx,c[j]);

			}

			ans+=mx;

		}

		printf ("%d\n",ans);

	

	}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.3132741284328517x):
//#include<bits/stdc++.h>

#define _CRT_SBCURE_NO_DEPRECATE

#include <set>

#include <map>

#include <cmath>

#include <queue>

#include <stack>

#include <vector>

#include <string>

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <iostream>

#include <algorithm>

#include <functional>

//#define UP(i,x,y) for(int i=x;i<=y;i++)

//#define DOWN(i,x,y) for(int i=x;i>=y;i--)

#define sdddd(x,y,z,k) scanf("%d%d%d%d", &x, &y, &z, &k)

#define sddd(x,y,z) scanf("%d%d%d", &x, &y, &z)

#define sdd(x,y) scanf("%d%d", &x, &y)

#define sd(x) scanf("%d", &x)

#define mp make_pair

#define pb push_back

#define lson k<<1

#define rson k<<1|1

#define mid (l+r)/2

#define ms(x, y) memset(x, y, sizeof x)

using namespace std;

typedef long long ll;

//typedef unsigned long long ull;

#define MOD 142857

const int maxn = 10100;

const int INF = 0x3f3f3f3f;

const ll LINF = 0x3f3f3f3f3f3f3f3f;

int n, m, s, t;

int len;

struct road

{

	int u, v, len, cost;

	int next;

};

struct node

{

    int v;

    int len;

    int cost;

    node(int v, int l, int c):v(v),len(l),cost(c){}

    friend bool operator <(node a, node b)

    {

        return a.len>b.len;

    }

};

road G[maxn*5];

int h[maxn];

int mx = -INF;

int d[maxn];

int c[maxn];

int path[maxn];

void dij()

{

    fill(d, d+n+1, INF);

    fill(path, path+n+1, -1);

    fill(c, c+n+1, 0);

    d[1] = 0;

    priority_queue<node> pque;

    pque.push(node(1, 0, 0));

    while(pque.size())

    {

        node p = pque.top(); pque.pop();

        int v = p.v;

        if(d[v] < p.len) continue;

        for(int i = h[v]; i != -1; i = G[i].next)

        {

            road e = G[i];

            if(d[e.v] > d[e.u] + e.len)

            {

                d[e.v] = d[e.u] + e.len;

                c[e.v] = c[e.u] + e.cost;

                path[e.v] = i;

                pque.push(node(e.v, d[e.v], c[e.v]));

            }

            else if(d[e.v] == d[e.u] + e.len)

            {

                if(path[e.v] != -1 && G[path[e.v]].cost > e.cost)

                {

                    path[e.v] = i;

                    pque.push(node(e.v, d[e.v], c[e.v]));

                }

            }

        }

    }

}

int main()

{

	//freopen("out.txt", "w", stdout);

    while(~sdd(n, m) && (n||m))

    {

        int ta, tb, tc, td;

        int len = 0;

        fill(h, h+n+1, -1);

        for(int i = 0; i < m; i++)

        {

            sdddd(ta, tb, tc, td);

            G[len].u = ta;

            G[len].v = tb;

            G[len].len = tc;

            G[len].cost = td;

            G[len].next = h[ta];

            h[ta] = len++;



            G[len].u = tb;

            G[len].v = ta;

            G[len].len = tc;

            G[len].cost = td;

            G[len].next = h[tb];

            h[tb] = len++;

        }

        dij();

        int ans = 0;

        for(int i = 1; i <= n; i++)

        {

            if(path[i]!=-1)

            {

                ans += G[path[i]].cost;

            }

        }

        printf("%d\n",ans);

    }



	return 0;

}