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

#include<cstring>

#include<queue>

#include<vector>

using namespace std;

#define INF 1000000000

#define pb push_back

#define maxn 10001

struct Edge{

	int from, to, dist, cost;

};

struct HeapNode{

	int d, u, c;

	bool operator < (const HeapNode& a)const{

		if(d==a.d)	return c>a.c;

		return d>a.d;

	}

};

inline void IN(int& x){

	x=0;

	char c=getchar();

	while(c<48 || c>57)	c=getchar();

	while(c>=48 && c<=57){

		x=x*10+c-48;

		c=getchar();

	}

}

int n, m;

vector<Edge> edges;

vector<int> G[maxn];

vector<int> V[maxn];

bool done[maxn];

int d[maxn], p[maxn], c[maxn];

int ans;

void init(){

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

		G[i].clear();

		V[i].clear();

	}

	edges.clear();

}

void add(int from, int to, int dist, int cost){

	edges.pb((Edge){from, to, dist, cost});

	m = edges.size();

	G[from].pb(m-1);

	V[from].pb(cost);

}

void dijkstra(int s){

	ans=0;

	priority_queue<HeapNode> Q;

	for(int i=1; i<=n; i++)	d[i]=INF;

	for(int i=1; i<=n; i++)	c[i]=INF;

	d[s]=0;

	c[s]=0;

	memset(done, 0, sizeof(done));

	Q.push((HeapNode){0,s,0});

	while(!Q.empty()){

		HeapNode x = Q.top(); Q.pop();

		int u=x.u;

		if(done[u])	continue;

		done[u]=1;

		ans += c[u];

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

			Edge& e = edges[G[u][i]];

			if(d[e.to]>d[u]+e.dist || (d[e.to]==d[u]+e.dist && c[e.to]>V[u][i])){

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

				p[e.to] = G[u][i];

				c[e.to] = V[u][i];

				Q.push((HeapNode){d[e.to],e.to,c[e.to]});

			}

		}

	}

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

}

int k;

int main(){

	while(1){

		IN(n); IN(k);

		if(!n && (!k))	break;

		int a, b, c, d;

		init();

		while(k--){

			IN(a); IN(b); IN(c); IN(d);

			add(a, b, c, d);

			add(b, a, c, d);

		}

		dijkstra(1);

	}

	return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.4264045545306816x):
#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;

}