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

#include <cstring>

const int SIZE = 10010;

const int MAX = 0x3f3f3f3f;



typedef struct Road

{

	int from;

	int to;

	int length;

	int cost;

	int next;

} Road;



int head[SIZE];

int dis[SIZE];

Road roads[SIZE * 5];

int front[SIZE];

bool visit[SIZE];



int city, road, capital;



void init()

{

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

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

	memset(visit, false, sizeof(visit));

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

	{

		dis[i] = MAX;

	}

	dis[1] = 0;

}



void dijkstra()

{

	while (true)

	{

		int pos = -1;

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

		{

			if (!visit[i] && (pos == -1 || dis[pos] > dis[i]))

			{

				pos = i;

			}

		}

		if (pos == -1)

		{

			break;

		}

		visit[pos] = true;

		for (int i = head[pos]; i != -1; i = roads[i].next)

		{

			int to = roads[i].to;

			if (dis[to] > dis[pos] + roads[i].length)

			{

				dis[to] = dis[pos] + roads[i].length;

				front[to] = i;

			}

			else if ((dis[to] == dis[pos] + roads[i].length) && front[to] != -1 && roads[i].cost < roads[front[to]].cost)

			{

				front[to] = i;

			}

		}

	}

}



int main()

{

	while (true)

	{

		std::cin >> city >> road;

		if (city == 0 && road == 0)

		{

			break;

		}

		init();

		int en = 0;

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

		{

			std::cin >> roads[en].from >> roads[en].to >> roads[en].length >> roads[en].cost;

			roads[en].next = head[roads[en].from];

			head[roads[en].from] = en;

			en++;

			roads[en].from = roads[en - 1].to;

			roads[en].to = roads[en - 1].from;

			roads[en].length = roads[en - 1].length;

			roads[en].cost = roads[en - 1].cost;

			roads[en].next = head[roads[en].from];

			head[roads[en].from] = en;

			en++;

		}

		dijkstra();

		int result = 0;

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

		{

			if (front[i] != -1)

			{

				result += roads[front[i]].cost;

			}

		}

		std::cout << result << std::endl;

	}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.1313606975670114x):
#include <iostream>

#include <cstdio>

#include <cstring>

#include <algorithm>

#include <queue>

using namespace std;



#define MAXN 20005

#define MAXE 40005

#define INF 0x3f3f3f3f



typedef int Type;



class Dijkstra

{

public:

    int head[MAXN],nxt[MAXE],cnt;

    Type d[MAXN];

    struct Edge

    {

        int v;

        Type dis;

        Type cost;

        Edge() {}

        Edge(int v,Type dis,Type cost):v(v),dis(dis),cost(cost) {}

        bool operator<(const Edge& ed) const

        {

            return dis>ed.dis;

        }

    } e[MAXE];

    bool vis[MAXN];



    //初始化，n?点数

    void init(int n)

    {

        cnt = 0;

        for(int i = 0; i<=n; i++) head[i] = -1;

    }



    inline void addEdge(int u,int v,Type dis,Type cost)

    {

        e[cnt] = Edge(v,dis,cost);

        int tmp = head[u];

        head[u] = cnt;

        nxt[cnt++] = tmp;

    }



    void dijkstra(int s,int t,int n)

    {

        for(int i = 0; i<=n; i++) d[i] = INF,vis[i] = false;

        d[s] = 0;

        priority_queue<Edge> q;

        q.push(Edge(s,0,0));

        while(!q.empty())

        {

            Edge ed = q.top();

            q.pop();

            vis[ed.v] = true;

            for(int i = head[ed.v]; ~i; i = nxt[i])

            {

                Edge ee = e[i];

                if(!vis[ee.v]&&d[ee.v]>d[ed.v]+ee.dis)

                {

                    d[ee.v] = d[ed.v]+ee.dis;

                    /*

                     *  最短路?

                    	p[ee.v] = MP(u,i);

                    */

                    q.push(Edge(ee.v,d[ee.v],ee.cost));

                }

            }

        }

    }



    void buildGraph(int m)

    {

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

        {

            int u,v,d,c;

            scanf("%d%d%d%d",&u,&v,&d,&c);

            addEdge(u,v,d,c);

            addEdge(v,u,d,c);

        }

    }



    Type getMinCost(int n)

    {

        int ans=0;

        for(int u=2; u<=n; u++) //首都不能?

        {

            int Min=INF;

            for(int j=head[u]; ~j; j=nxt[j])

            {

                Edge ee = e[j];

                if(d[u]==d[ee.v]+ee.dis && ee.cost<Min) //找??足?先距?最短，然后?用最低的那个最低?用

                    Min=ee.cost;

            }

            ans+=Min;

        }

        return ans;

    }

} dij;



int main()

{

    int n,m;

    while(~scanf("%d%d",&n,&m))

    {

        if(n==0 && m==0)

            break;

        dij.init(n);

        dij.buildGraph(m);

        dij.dijkstra(1,n,n);

        int ans=dij.getMinCost(n);

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

    }

    return 0;

}