/*

    LibreOJ #115. 无源汇有上下界可行流

    板子题

    我也就会写写板子题了。。

*/

#include <cstdio>

#include <iostream>

#include <queue>

#include <cstring>

const int BUF = ;

char Buf[BUF], *buf = Buf;

void read (int &now)

{

    for (now = ; !isdigit (*buf); ++ buf);

    for (; isdigit (*buf); now = now *  + *buf - '', ++ buf);

}

inline int min (int a, int b)

{

    return a < b ? a : b;

}

#define Max 800

#define INF 1e8

int _S, _T;

int low[Max << ], _in[Max];

class Net_Flow

{

    private : 

        int to[Max << ], _next[Max << ], flow[Max << ];

        int C, list[Max << ], deep[Max << ], _tech[Max << ];

        int S, T;

    public :

        inline void In (int u, int v, int w)

        {

            to[++ C] = v, _next[C] = list[u], list[u] = C;

            to[++ C] = u, _next[C] = list[v], list[v] = C;

            flow[C] = , flow[C - ] = w;

        }

        void Clear ()

        {

            C = , S = _S, T = _T;

        }

        int Flowing (int now, int Flow)

        {

            if (now == T || Flow == )

                return Flow;

            register int res = , pos;

            for (int &i = _tech[now]; i; i = _next[i])

            {

                if (deep[to[i]] != deep[now] +  || flow[i] == )

                    continue;

                pos = Flowing (to[i], min (flow[i], Flow));

                if (pos > )

                {

                    flow[i] -= pos, res += pos, flow[i ^ ] += pos;

                    Flow -= pos; if (Flow <= ) break;

                }

            }

            if (res != Flow) deep[now] = -;

            return res;

        }

        bool Bfs ()

        {

            std :: queue <int> Queue;

               memset (deep, -, sizeof deep);

            Queue.push (S), deep[S] = ; register int i, now;

            for (; !Queue.empty (); Queue.pop ())

            {

                now = Queue.front ();

                for (i = list[now]; i; i = _next[i])

                    if (deep[to[i]] <  && flow[i])

                    {

                        deep[to[i]] = deep[now] + ;

                        if (to[i] == T)

                            return true;

                        Queue.push (to[i]);

                    }

            }

            return deep[T] != -;

        }

        int Dinic ()

        {

            int res = ;

            for (; Bfs (); )

            {

                for (int i = S; i <= T; ++ i)

                    _tech[i] = list[i];

                res += Flowing (S, INF);

            }

            return res;

        }

        void Print (const int &M)

        {

            printf ("YES\n");

            for (int i = ; i <= M; ++ i)

                printf ("%d\n", low[i] + flow[i <<  | ]);

        }

};

Net_Flow Flow;

//#define Local

int Main ()

{

#ifdef Local 

    freopen ("yukari.wife", "r", stdin);

#endif

    fread (buf, , BUF, stdin);

    int N, M;

    read (N);

    read (M);

    int u, v, up;

    _S = , _T = N + , Flow.Clear ();

    for (int i = ; i <= M; ++ i)

    {

        read (u), read (v), read (low[i]), read (up);

        Flow.In (u, v, up - low[i]);

        _in[u] -= low[i], _in[v] += low[i];

    }

    int Total = ;

    for (int i = ; i <= N; ++ i)

        if (_in[i] > )

            Total += _in[i], Flow.In (_S, i, _in[i]);

        else if (_in[i] < )

               Flow.In (i, _T, -_in[i]);

    if (Flow.Dinic () != Total)

        return printf ("NO"), ;

    else Flow.Print (M);

    return ;

}

int ZlycerQan = Main ();

int main (int argc, char *argv[]) {; }