//一个建图的破错误，浪费了我一上午，孤独的我伤不起

#include <bits/stdc++.h>
using namespace std;

const int N=220, M=22000, inf=1e9;
int ver[M],nxt[M],fl[M],low[M],head[N],tot=1;
int q[N],d[N],nh[N],A[N]; //A:All
int n,m,S,T;

void add(int x,int y,int lw,int up){
    ver[++tot]=y,nxt[tot]=head[x],head[x]=tot;
    low[tot]=lw,fl[tot]=up-lw;
}

bool bfs(){
    memset(d,0,sizeof d);
    d[S]=1,q[0]=S,nh[S]=head[S];

    int hh=0,tt=1;
    while(hh<tt){
        int x=q[hh++];
        for(int i=head[x];i;i=nxt[i]){
            int y=ver[i];
            if(d[y] || !fl[i])continue;

            d[y]=d[x]+1, nh[y]=head[y];
            if(y==T)return true;
            q[tt++]=y;
        }
    }
    return false;
}

int find(int x,int limit){
    if(x==T)return limit;

    int flow=0;
    for(int i=nh[x];i && flow<limit;i=nxt[i]){
        nh[x]=i;
        int y=ver[i];
        if(d[y]!=d[x]+1 || !fl[i])continue;

        int t=find(y,min(fl[i],limit-flow));
        if(t)flow+=t, fl[i]-=t, fl[i^1]+=t;
        else d[y]=0;
    }
    return flow;
}

int dinic(){
    int res=0,flow;
    for(;bfs();)
        while(flow=find(S,inf))res+=flow;
    return res;
}

int main(){
    cin>>n>>m;
    S=0, T=n+1;
    int a,b,c,d;
    for(int i=1;i<=m;i++){
        cin>>a>>b>>c>>d;
        add(a,b,c,d), add(b,a,0,0);
        A[a]-=c, A[b]+=c;
    }
    int sum=0;
    for(int i=1;i<=n;i++){
        if(A[i]>0) add(S,i,0,A[i]), add(i,S,0,0),sum+=A[i]; 
        if(A[i]<0) add(i,T,0,-A[i]),add(T,i,0,0);
    }

    int yes=(dinic()==sum);
    puts(yes ? "YES" : "NO");
    for(int i=2;yes && i<=2*m;i+=2)
        cout<<fl[i^1]+low[i]<<endl;
    return 0;
}