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

#include <cstdlib>

#include <cstring>

#include <queue>

#include <algorithm>

using namespace std;

#define MAXN 10010

#define MAXM 40010



int n,m;

struct node

{

    int v,d,c,next;

}e[MAXM];

int ecnt,pre[MAXN],dis[MAXN],co[MAXN];

bool vis[MAXN];

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

{

    e[ecnt].v=v;

    e[ecnt].d=d;

    e[ecnt].c=c;

    e[ecnt].next=pre[u];

    pre[u]=ecnt++;

}

void spfa()

{

    queue<int> q;

    q.push(1);

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

    memset(dis,0x3f,sizeof(dis));

    memset(co,0x3f,sizeof(co));

    dis[1]=co[1]=0;

    while (!q.empty())

    {

        int u=q.front();

        q.pop();

        vis[u]=0;

        for (int i=pre[u];i!=-1;i=e[i].next)

        {

            int v=e[i].v;

            if ((dis[v]>dis[u]+e[i].d)||(dis[v]==dis[u]+e[i].d&&co[v]>e[i].c))

            {

                dis[v]=dis[u]+e[i].d;

                co[v]=e[i].c;

                if (!vis[v])

                {

                    vis[v]=1;

                    q.push(v);

                }

            }

        }

    }

}

int main()

{

    //freopen("/home/moor/Code/input","r",stdin);

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

    {

        ecnt=0;

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

        int u,v,d,c;

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

        {

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

            add(u,v,d,c);

            add(v,u,d,c);

        }

        spfa();

        int ans=0;

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

            ans+=co[i];

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

    }

    return 0;

}

// Faster C++ solution for the same problem (measured speedup: 1.0975582446456558x):
#include <cstdio>

#include <cstring>

#include <queue>

using namespace std;

const int INF = 0x3f3f3f3f;

struct node

{

    int to, w, c, next;

} edge[50005];

int head[10005], ip, cost[10005], dis[10005], n, m;

bool vis[10005];

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

{

    edge[ip].to = v;

    edge[ip].w = d;

    edge[ip].c = c;

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

    head[u] = ip++;

}

void spfa(int s)

{

    queue<int> q;

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

        cost[i] = dis[i] = INF;

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

    dis[s] = 0;

    cost[s] = 0;

    vis[s] = 1;

    q.push(s);

    while (!q.empty())

    {

        int u = q.front();

        q.pop();

        vis[u] = 0;

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

        {

            int to = edge[i].to;

            int w = edge[i].w;

            if(dis[to] > dis[u] + w||(dis[to] == dis[u]+w&&cost[to] > edge[i].c))

            {

                dis[to] = dis[u] + w;

                cost[to] = edge[i].c;

                if(!vis[to])

                {

                    q.push(to);

                    vis[to] = 1;

                }

            }

        }

    }

}

int main()

{

    while (scanf("%d %d", &n, &m) != EOF)

    {

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

            break;

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

        ip = 0;

        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);

        }

        spfa(1);

        int ans = 0;

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

            ans += cost[i];

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

    }

    return 0;

}