#include<iostream>
#include<cstdio>
#include<cstring>
#include<cmath>
#include<queue>
using namespace std;
const int MAXN=2000001;
inline char nc()
{
    static char buf[MAXN],*p1=buf,*p2=buf;
    return p1==p2&&(p2=(p1=buf)+fread(buf,1,MAXN,stdin),p1==p2)?EOF:*p1++;
}
inline int read()
{
    char c=nc();int x=0,f=1;
    while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1;c=nc();}
    while(c>=‘0‘&&c<=‘9‘){x=x*10+c-‘0‘;c=nc();}
    return x*f;
}
int n,m,s,t;
struct node
{
    int u,v,flow,nxt;
}edge[MAXN];
int head[MAXN],cur[MAXN],A[MAXN];
int num=0;
void AddEdge(int x,int y,int z)
{
    edge[num].u=x;
    edge[num].v=y;
    edge[num].flow=z;
    edge[num].nxt=head[x];
    head[x]=num++;
}
void add_edge(int x,int y,int z)
{
    AddEdge(x,y,z);
    AddEdge(y,x,0);
}
int deep[MAXN],L[MAXN];
bool BFS()
{
    memset(deep,0,sizeof(deep));
    deep[s]=1;
    queue<int>q;
    q.push(s);
    while(q.size()!=0)
    {
        int p=q.front();
        q.pop();
        for(int i=head[p];i!=-1;i=edge[i].nxt)
            if(!deep[edge[i].v]&&edge[i].flow)
            {
                deep[edge[i].v]=deep[edge[i].u]+1;q.push(edge[i].v);
                if(edge[i].v==t) return 1;
            }
                
    }
    return deep[t];
    
}
int DFS(int now,int nowflow)
{
    if(now==t||nowflow<=0)
        return nowflow;
    int totflow=0;
    for(int &i=cur[now];i!=-1;i=edge[i].nxt)
    {
        if(deep[edge[i].v]==deep[edge[i].u]+1&&edge[i].flow)
        {
            int canflow=DFS(edge[i].v,min(nowflow,edge[i].flow));
            edge[i].flow-=canflow;
            edge[i^1].flow+=canflow;
            totflow+=canflow;
            nowflow-=canflow;
            if(nowflow<=0)
                break;
        }
    }
    return totflow;
}
int Dinic()
{
    int ans=0;
    while(BFS())
    {
        for(int i=0;i<=n;i++)
            cur[i]=head[i];
        ans+=DFS(s,1e8);
    }
    return ans;
}
int main()
{
    #ifdef WIN32
    freopen("a.in","r",stdin);
    #else
    #endif
    n=read();m=read();s=0;t=n+1;
    memset(head,-1,sizeof(head));
    for(int i=1;i<=m;i++)
    {
        int x=read(),y=read(),lower=read(),upper=read();L[i-1]=lower;
        add_edge(x,y,upper-lower);A[x]-=lower;A[y]+=lower;
    }
    int sum=0;
    for(int i=1;i<=n;i++)
    {
        if(A[i]>0) sum+=A[i],add_edge(s,i,A[i]);
        else add_edge(i,t,-A[i]);
    }
    if(Dinic()!=sum) printf("NO");
    else
    {
        printf("YES\n");
        for(int i=0;i<m;i++)
            printf("%d\n",edge[i*2|1].flow+L[i]);
    }
    return  0;
}