// 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: 1.635362876211028x):
#include <cstdio>

#include <iostream>

#include <cstring>

#include <string>

#include <algorithm>

#include <vector>

#include <queue>

const int maxn = 10007;

const int inf =1e9;

using namespace std;

struct node{

	int to,d,c;

	node(){}

	node (int to,int d,int c):to(to),d(d),c(c){}

};

vector<node>mp[maxn];

int dis[maxn],cost[maxn],n,m,ans = 0;

void init(){

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

	{

		mp[i].clear();

		dis[i] = inf;

		cost[i]  = 0;

	}

}

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

{

	mp[u].push_back(node(v,d,c));

}

int main(){

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

	{

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

		init();

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

		{

			int u,v,d,c;

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

			add(u,v,d,c);

			add(v,u,d,c);

		}

		priority_queue<pair<int,int> >q;

		dis[1]=0;

		cost[1]=0;

		

		q.push (make_pair(-dis[1],1)) ;

		while(!q.empty())

		{

			int now = q.top().second;

			q.pop();

			for(int i=0;i<mp[now].size();i++)

			{

				int v=mp[now][i].to;

				int d=mp[now][i].d;

				int c=mp[now][i].c;

				if(dis[v]>dis[now]+d)

				{

					dis[v] = dis[now]+d;

					//ans -=cost[v];

					//cost[v] = cost[now]+c;

					//ans +=cost[v];

					q.push (make_pair(-dis[v],v));

				}

			}

		}

		ans = 0;

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

		{

			int minc = inf;

			for(int j=0;j<mp[i].size();j++)

			{

				node tmp = mp[i][j];

				if(tmp.d+dis[tmp.to]==dis[i]&&minc>tmp.c)

				{

					minc = mp[i][j].c;

				}

			}

			ans += minc;

		}

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

	}

	return 0;

}