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

#include <cstdlib>

#include <cstring>

#include <queue>

#include <algorithm>

using namespace std;

#define MAXN 10010

#define MAXM 40010



int n,m;

struct node

{

    int v,d,c,next;

}e[MAXM];

int ecnt,pre[MAXN],dis[MAXN],co[MAXN];

bool vis[MAXN];

void add(int u,int v,int d,int c)

{

    e[ecnt].v=v;

    e[ecnt].d=d;

    e[ecnt].c=c;

    e[ecnt].next=pre[u];

    pre[u]=ecnt++;

}

void spfa()

{

    queue<int> q;

    q.push(1);

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

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

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

    dis[1]=co[1]=0;

    while (!q.empty())

    {

        int u=q.front();

        q.pop();

        vis[u]=0;

        for (int i=pre[u];i!=-1;i=e[i].next)

        {

            int v=e[i].v;

            if ((dis[v]>dis[u]+e[i].d)||(dis[v]==dis[u]+e[i].d&&co[v]>e[i].c))

            {

                dis[v]=dis[u]+e[i].d;

                co[v]=e[i].c;

                if (!vis[v])

                {

                    vis[v]=1;

                    q.push(v);

                }

            }

        }

    }

}

int main()

{

    //freopen("/home/moor/Code/input","r",stdin);

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

    {

        ecnt=0;

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

        int u,v,d,c;

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

        {

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

            add(u,v,d,c);

            add(v,u,d,c);

        }

        spfa();

        int ans=0;

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

            ans+=co[i];

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

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.0976618161062373x):
#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;

}