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

#include <algorithm>

#include <cstdio>

#include <queue>

#include <cstring>

#define INF 0x3f3f3f



using namespace std;

const int MAX_V=100001;

struct node

{

    int to, dis, cost, next;

}edge[MAX_V];



int head[MAX_V], d[MAX_V], mcost[MAX_V];//mcoat一个?点??一条?

bool vis[MAX_V];

int n, m, cnt;



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

{

    edge[cnt].to=v;

    edge[cnt].dis=d;

    edge[cnt].cost=c;

    edge[cnt].next=head[u];

    head[u]=cnt++;

}



int spfa(int x)

{

    d[x]=0;         //必?！！！

    queue<int> que;

    que.push(x);

    vis[x]=true;

    while(!que.empty())

    {

        int u=que.front();

        que.pop();

        vis[u]=false;

        for(int i=head[u]; i!=-1; i=edge[i].next)

        {

            node e = edge[i];

            if(d[e.to] > d[u]+e.dis)

            {

                mcost[e.to]=e.cost;     ////??最小花?

                d[e.to] = d[u]+e.dis;

                if(!vis[e.to])

                {

                    que.push(e.to);

                    vis[e.to]=true;

                }

            }

            else if(d[u]+e.dis==d[e.to] && e.cost<mcost[e.to])   ////??最小花?

                {

                    mcost[e.to]=e.cost;

                }

        }

    }

    int ans=0;

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

    {

     //   printf("\n%d\n", mcost[i]);

        ans+=mcost[i];

    }

    return ans;

}



int main()

{

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

    {

        cnt=0;          //从0?始！！！

        memset(head, -1, sizeof(head)); //初始化在前面！！！！

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

        {

            int u, v, d, c;

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

            add_edge(u,v,d,c);

            add_edge(v,u,d,c);      //双向的路！！！

        }



        //初始化

        memset(mcost, 0, sizeof(mcost));

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

        fill(vis, vis+n+1, false);



        int ans=spfa(1);

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

    }



    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 2.0515366083604913x):
#include <cstdio>

#include <cstring>

#include <queue>

using namespace std;

const int INF = 0x3f3f3f3f;

struct node

{

    int to, w, c, next;

} edge[50005];

int head[10005], ip, cost[10005], dis[10005], n, m;

bool vis[10005];

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

{

    edge[ip].to = v;

    edge[ip].w = d;

    edge[ip].c = c;

    edge[ip].next = head[u];

    head[u] = ip++;

}

void spfa(int s)

{

    queue<int> q;

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

        cost[i] = dis[i] = INF;

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

    dis[s] = 0;

    cost[s] = 0;

    vis[s] = 1;

    q.push(s);

    while (!q.empty())

    {

        int u = q.front();

        q.pop();

        vis[u] = 0;

        for(int i = head[u];i != -1;i = edge[i].next)

        {

            int to = edge[i].to;

            int w = edge[i].w;

            if(dis[to] > dis[u] + w||(dis[to] == dis[u]+w&&cost[to] > edge[i].c))

            {

                dis[to] = dis[u] + w;

                cost[to] = edge[i].c;

                if(!vis[to])

                {

                    q.push(to);

                    vis[to] = 1;

                }

            }

        }

    }

}

int main()

{

    while (scanf("%d %d", &n, &m) != EOF)

    {

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

            break;

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

        ip = 0;

        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);

        }

        spfa(1);

        int ans = 0;

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

            ans += cost[i];

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

    }

    return 0;

}