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

#include<iostream>

#include<algorithm>

#include<vector>

#include<queue>

#define MAX_V 10006

#define INF 0x3fffffff

using namespace std;

struct edge{

    int to,cost,dis;

    };

typedef pair<int,int> P;

int V;

vector<edge> G[MAX_V];

int d[MAX_V];



void dij(int s){

    priority_queue<P,vector<P>,greater<P> > que;

    fill(d,d+V,INF);

    d[s]=0;

    que.push(P(0,s));

    while(!que.empty()){

        P p=que.top();que.pop();

        int v=p.second;

        if(d[v]<p.first)continue;

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

            edge e=G[v][i];

            if(d[e.to]>d[v]+e.cost){

                d[e.to]=d[v]+e.cost;

                que.push(P(d[e.to],e.to));

            }

        }

    }

    int ans=0;



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

        int mimcost=INF;

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

            if(d[G[i][j].to]+G[i][j].cost==d[i]&&G[i][j].dis<mimcost){



                mimcost=G[i][j].dis;

                //cout<<mimcost<<endl;

            }

        }

        //cout<<mimcost<<endl;

        ans+=mimcost;

    }

    cout<<ans<<endl;



}



int main(){

   // freopen("1.txt","r",stdin);

    int M;

    while(cin>>V>>M){

        if(V==0&&M==0)break;

        for(int i=0;i<V;i++)G[i].clear();

        while(M--){

            int a,b,t,c;

            cin>>a>>b>>t>>c;

            a--;b--;

            edge tmp;

            tmp.to=b;

            tmp.cost=t;

            tmp.dis=c;

            G[a].push_back(tmp);

            tmp.to=a;

            G[b].push_back(tmp);

        }

        dij(0);

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.2719643099792561x):
//#include<bits/stdc++.h>

#define _CRT_SBCURE_NO_DEPRECATE

#include <set>

#include <map>

#include <cmath>

#include <queue>

#include <stack>

#include <vector>

#include <string>

#include <cstdio>

#include <cstdlib>

#include <cstring>

#include <iostream>

#include <algorithm>

#include <functional>

//#define UP(i,x,y) for(int i=x;i<=y;i++)

//#define DOWN(i,x,y) for(int i=x;i>=y;i--)

#define sdddd(x,y,z,k) scanf("%d%d%d%d", &x, &y, &z, &k)

#define sddd(x,y,z) scanf("%d%d%d", &x, &y, &z)

#define sdd(x,y) scanf("%d%d", &x, &y)

#define sd(x) scanf("%d", &x)

#define mp make_pair

#define pb push_back

#define lson k<<1

#define rson k<<1|1

#define mid (l+r)/2

#define ms(x, y) memset(x, y, sizeof x)

using namespace std;

typedef long long ll;

//typedef unsigned long long ull;

#define MOD 142857

const int maxn = 10100;

const int INF = 0x3f3f3f3f;

const ll LINF = 0x3f3f3f3f3f3f3f3f;

int n, m, s, t;

int len;

struct road

{

	int u, v, len, cost;

	int next;

};

struct node

{

    int v;

    int len;

    int cost;

    node(int v, int l, int c):v(v),len(l),cost(c){}

    friend bool operator <(node a, node b)

    {

        return a.len>b.len;

    }

};

road G[maxn*5];

int h[maxn];

int mx = -INF;

int d[maxn];

int c[maxn];

int path[maxn];

void dij()

{

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

    fill(path, path+n+1, -1);

    fill(c, c+n+1, 0);

    d[1] = 0;

    priority_queue<node> pque;

    pque.push(node(1, 0, 0));

    while(pque.size())

    {

        node p = pque.top(); pque.pop();

        int v = p.v;

        if(d[v] < p.len) continue;

        for(int i = h[v]; i != -1; i = G[i].next)

        {

            road e = G[i];

            if(d[e.v] > d[e.u] + e.len)

            {

                d[e.v] = d[e.u] + e.len;

                c[e.v] = c[e.u] + e.cost;

                path[e.v] = i;

                pque.push(node(e.v, d[e.v], c[e.v]));

            }

            else if(d[e.v] == d[e.u] + e.len)

            {

                if(path[e.v] != -1 && G[path[e.v]].cost > e.cost)

                {

                    path[e.v] = i;

                    pque.push(node(e.v, d[e.v], c[e.v]));

                }

            }

        }

    }

}

int main()

{

	//freopen("out.txt", "w", stdout);

    while(~sdd(n, m) && (n||m))

    {

        int ta, tb, tc, td;

        int len = 0;

        fill(h, h+n+1, -1);

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

        {

            sdddd(ta, tb, tc, td);

            G[len].u = ta;

            G[len].v = tb;

            G[len].len = tc;

            G[len].cost = td;

            G[len].next = h[ta];

            h[ta] = len++;



            G[len].u = tb;

            G[len].v = ta;

            G[len].len = tc;

            G[len].cost = td;

            G[len].next = h[tb];

            h[tb] = len++;

        }

        dij();

        int ans = 0;

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

        {

            if(path[i]!=-1)

            {

                ans += G[path[i]].cost;

            }

        }

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

    }



	return 0;

}