// Slower C++ solution:
#include <bits/stdc++.h>

using namespace std;



typedef long long ll;

const int N = 10005;

const int M = 1000000007;



int n, m;

typedef int wtype;

struct Edge { int v; wtype d, c; };

vector<Edge> e[N];

wtype dist[N], cost[N];

int pre[N];

bool vis[N];

int SPFA(int src) {

  memset(dist, 0x3f, sizeof(dist)); dist[src] = 0;

  memset(cost, 0x3f, sizeof(cost)); cost[src] = 0;

  memset(vis, 0, sizeof(vis)); vis[src] = true;

  stack<int> que; que.push(src);

  while (!que.empty()) {

    int u = que.top(); que.pop();

    vis[u] = false;

    for (int i = 0; i < (int)e[u].size(); i++) {

      int v = e[u][i].v; wtype d = e[u][i].d, c = e[u][i].c;

      if (dist[v] > dist[u] + d || (dist[v] == dist[u] + d && cost[v] != 0x3f3f3f3f && cost[v] > c)) {

        dist[v] = dist[u] + d; cost[v] = c;

        if (!vis[v]) { vis[v] = true; que.push(v); }

      }

    }

  }

  int ret = 0;

  for (int i = 1; i <= n; i++) { ret += cost[i]; }

  return ret;

}



int main() {

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

    for (int i = 1; i <= n; i++) { e[i].clear(); }

    for (int i = 0, u, v, d, c; i < m; i++) {

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

      e[u].push_back((Edge) {v, d, c});

      e[v].push_back((Edge) {u, d, c});

    }

    printf("%d\n", SPFA(1));

  }

}

// Faster C++ solution for the same problem (measured speedup: 1.369991155984998x):
#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;

}