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

using namespace std;

struct node{

    int next,d,c;

};

const int maxn=10005;

int n,m;

int d[maxn],c[maxn];

bool vis[maxn];

void init()

{

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

        d[i]=c[i]=1e9,vis[i]=0;

}

int main()

{

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

    {

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

        init();vector<node> v[maxn];

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

        {

            int x,y,d,c;

            scanf("%d%d%d%d",&x,&y,&d,&c);

            v[x].push_back(node{y,d,c});

            v[y].push_back(node{x,d,c});

        }

        queue<int> q;

        q.push(1);

        d[1]=c[1]=0;vis[1]=1;

        while(!q.empty())

        {

            int u=q.front();q.pop();vis[u]=0;

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

            {

                int nx=v[u][i].next;

                if(d[nx]==d[u]+v[u][i].d&&c[nx]>v[u][i].c){

                        c[nx]=v[u][i].c;

                }

                if(d[nx]>d[u]+v[u][i].d)

                {

                    d[nx]=d[u]+v[u][i].d;

                    c[nx]=v[u][i].c;

                    if(vis[nx]) continue;

                    vis[nx]=1;

                    q.push(nx);

                }

            }

        }

        int ans=0;

        for(int i=2;i<=n;i++) ans+=c[i];

        cout<<ans<<endl;

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.2965934019988x):
#include <cstdio>

#include <cstring>

#include <algorithm>

#include <queue>



using namespace std;



const int inf = 0x3f3f3f3f;

const int N = 10414;

const int M = 40414;



struct Edge{

	int u, v, d, c;

	int next;

}edge[M];



int cnt, head[N];

int op, tp, link[N];

int vis[N], dis[N], cost[N];

queue<int>q;



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

void spfa(int n);



int main(){

	int n, m, i, u, v, d, c;

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

		cnt = 0;

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

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

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

			add_edge(u, v, d, c);

			add_edge(v, u, d, c);

		}

		spfa(n);

	}

	return 0;

}

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

	edge[cnt].u = u;

	edge[cnt].v = v;

	edge[cnt].d = d;

	edge[cnt].c = c;

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

	head[u] = cnt++;

}

void spfa(int n)

{

    int v, d, c;

    while(!q.empty())q.pop();

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

    memset(dis, inf, sizeof(dis));

    memset(cost, inf, sizeof(cost));

    dis[1]=0;

    cost[1]=0;

    vis[1]=true;

    q.push(1);

    while(!q.empty())

    {

        int u=q.front();

        q.pop();

        vis[u]=false;

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

        {

            v = edge[i].v;

            d = edge[i].d;

            c = edge[i].c;

            if(dis[v] > dis[u] + d||(dis[v] == dis[u] + d && cost[v] > c))//有多条最短路时，取花费最小的

            {

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

                cost[v] = c;

                if(!vis[v])

                {

                    q.push(v);

                    vis[v]=true;

                }

            }

        }

    }

    int sum = 0;

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

    	sum += cost[i];

    }

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

    return;

}