2 1
1 1
2 1
 8 12
-6 2 -3 2 6 -7 1 -5
2 1
5 6
1 6
1 4
8 2
2 7
2 5
8 3
8 4
3 7
7 6
3 1
 10 13
3 4 -3 8 6 4 -5 1 3 -7
9 5
9 2
10 3
1 4
3 5
9 1
6 10
10 4
3 1
2 7
1 6
1 7
7 8
 43 52
-23 -18 -35 21 -12 38 -35 -11 28 -20 27 -5 9 -19 -39 -25 -32 32 -36 28 11 37 1 -25 -22 9 -15 21 25 -39 10 36 -30 -40 22 26 25 -27 -22 -38 -1 18 -13
33 40
31 23
30 26
21 17
6 2
41 19
32 39
32 23
13 14
25 35
31 30
19 32
25 22
34 36
7 40
23 6
40 12
1 3
23 43
36 13
18 33
17 32
7 3
21 34
41 35
20 7
23 1
41 8
25 19
20 29
42 5
40 21
9 37
17 41
30 10
41 18
39 1
20 24
20 4
42 3
20 25
5 16
31 9
42 28
10 11
19 42
31 38
25 2
31 27
17 25
13 15
31 20
 2 1
1 1
1 2
 5 7
4 1 5 3 -1
2 4
5 4
5 2
1 5
1 2
4 1
1 3
 10 12
5 1 1 8 -8 10 -3 -2 1 7
5 3
8 2
10 9
4 6
5 6
4 5
5 10
4 7
8 4
3 1
3 6
6 10
 20 40
-9 -10 -9 15 -3 -5 -17 -10 -6 2 -13 19 10 -15 15 -14 17 0 7 -8
3 17
6 18
15 12
2 5
18 3
16 20
6 17
20 10
10 18
9 12
15 3
6 4
15 16
20 6
20 9
9 4
4 8
14 5
11 7
12 11
3 13
14 19
7 17
16 14
19 7
12 13
14 13
13 11
9 14
13 17
8 19
5 20
2 17
2 16
12 5
8 1
20 3
6 2
5 18
13 8

YES
                                                               1
 NO
 YES
                                                              -7
                                                              10
                                                             -16
                                                               3
                                                              13
                                                               0
                                                               4
                                                               5
                                                               0
                                                              -6
                                                               0
                                                               0
                                                               1
 NO
 YES
                                                               1
 YES
                                                               2
                                                               1
                                                              -1
                                                              -1
                                                               0
                                                               0
                                                               5
 YES
-4
1
1
17
-7
-3
6
-3
-3
5
0
0
 YES
                                                             -30
                                                             -21
                                                             -23
                                                             -10
                                                              21
                                                             -52
                                                               0
                                                               2
                                                               0
                                                              -9
                                                               0
                                                              16
                                                              38
                                                               0
                                                              42
                                                               0
                                                              -1
                                                               7
                                                             -64
                                                              51
                                                               0
                                                               7
                                                              47
                                                               0
                                                               0
                                                               0
                                                              10
                                                               0
                                                             -39
                                                               0
                                                               0
                                                               0
                                                               0
                                                               0
                                                               0
                                                              -9
                                                               0
                                                               0
                                                               0
                                                               0

import java.io.*;
import java.util.*;

public class D901 {
	
	int n;
	LinkedList<Edge>[] adj;
	long[] c;
	HashMap<Edge,Edge> edges;
	Edge[] edgeArray;
	
	private void solve() throws Exception {
		n = nextInt();
		int m = nextInt();
		
		edgeArray = new Edge[m];
		edges = new HashMap<Edge,Edge>();
		

		c = new long[n];
		for(int i = 0; i < n; i++) c[i] = nextInt();
			
		
		adj = new LinkedList[n];
		for(int i = 0; i < n; i++) adj[i] = new LinkedList<Edge>();
		for(int i = 0; i < m; i++){
			int u = nextInt()-1;
			int v = nextInt()-1;
			Edge e = new Edge(u, v);
			edgeArray[i] = e;
			adj[u].addLast(e);
			adj[v].addLast(e);
			edges.put(e,e);
		}
		
		visited = new boolean[n];
		dfsOddDegree(0);

		
		bfs();
		boolean ok = true;
		if(oddCycle != null){
			dfsBipartite(oddCycle[0]);
			for(int i = 0; i < oddCycle.length; i++) {
				 int u = oddCycle[i];
				 int v = oddCycle[(i+1)%oddCycle.length];
				 Edge e = edges.get(new Edge(u,v));
				 e.add((i%2==0?1L:-1L)*c[oddCycle[0]]/2L); 
			 }
		} else{//bipartite
			dfsBipartite(0);
			if(c[0] != 0L) ok = false; 
		}
		if(ok){
			out.println("YES");
			for(int i = 0; i < m; i++) out.println(edgeArray[i].w);
		}else out.println("NO");
	}
	
	void dfsBipartite(int u){
		visited = new boolean[n];
		visit(u);
	}
	
	void dfs(){
		 visited = new boolean[n];
		 int t = oddCycle.length;
		 for(int i = 0; i < t; i++) visited[oddCycle[i]] = true;
		 for(int i = 0; i < t; i++) visit(oddCycle[i]);
		 long last = 0;
		 for(int i = 0; i < t; i++) {
			 int u = oddCycle[i];
			 int v = oddCycle[(i+1)%t];
			 Edge e = edges.get(new Edge(u,v));
			 last = c[u]/2L-last;
			 e.add(last);			 
		 }
		 last = 0;
		 for(int i = t-1; i > 0; i--) {
			 int u = oddCycle[i];
			 int v = oddCycle[i-1];
			 Edge e = edges.get(new Edge(u,v));
			 last = c[u]/2L-last;
			 e.add(last);			 
		 }
		
	}
	
	boolean[] visited;
	
	void visit(int u){
		visited[u] = true;
		for(Edge e:adj[u]){
			int v = e.other(u);
			if(!visited[v]) {
				visit(v);
				c[u] -= c[v];
				e.add(c[v]);
			}
		}
	}
	
	int[] p;
	
	Integer[] oddCycle;
	
	void bfs(){
		color = new int[n];
		p = new int[n];
		Arrays.fill(color, -1);
		Arrays.fill(p, -1);
		LinkedList<Integer> queue = new LinkedList<Integer>();
		queue.addLast(0);
		color[0] = 0;
		while(!queue.isEmpty()){
			int u = queue.removeFirst();
			for(Edge e : adj[u]){
				int v = e.other(u);
				if(color[v] < 0){
					color[v] = 1-color[u];
					p[v] = u;
					queue.addLast(v);
				} else if(color[v] + color[u] != 1){
					oddCycle = oddCycle(u,v);
					return;
				}
			}
		}
	}
	
	Integer[] oddCycle(int u, int v){
		Integer[] pathU = pathToRoot(u);
		Integer[] pathV = pathToRoot(v);
		int idx = 0;
		while(idx < pathU.length && pathU[idx] == pathV[idx]) idx++;
		LinkedList<Integer> cycleList = new LinkedList<Integer>();
		for(int i = idx-1; i < pathU.length; i++) cycleList.addLast(pathU[i]);
		for(int i = pathV.length-1; i >= idx; i--) cycleList.addLast(pathV[i]);
		
		return cycleList.toArray(new Integer[0]);
	}
	
	Integer[] pathToRoot(int u){
		LinkedList<Integer> pathUList = new LinkedList<Integer>();
		while(u >= 0) {
			pathUList.addFirst(u);
			u = p[u];
		}
		return pathUList.toArray(new Integer[0]);
	}
	
	int[] color;
	
	boolean dfsOddDegree(int u){
		visited[u] = true;
		boolean odd = (adj[u].size()%2==1);
		for(Edge e:adj[u]){
			int v = e.other(u);
			if(!visited[v]) {
				boolean nextOdd = dfsOddDegree(v); 
				if(nextOdd)	{
					e.add(1L);
					c[e.u]--;
					c[e.v]--;
				}
				odd = odd ^ nextOdd;
			}
		}
		return odd;
	}

	public static void main(String[] args) {
		new D901().run();
	}

	private BufferedReader in;
	private PrintWriter out;
	private StringTokenizer tokenizer;

	public void run() {
		try {
			in = new BufferedReader(new InputStreamReader(System.in));
			tokenizer = null;
			out = new PrintWriter(System.out);
			solve();
			in.close();
			out.close();
		} catch (Exception e) {
			e.printStackTrace();
			System.exit(1);
		}
	}

	private int nextInt() throws IOException {
		return Integer.parseInt(nextToken());
	}

	private long nextLong() throws IOException {
		return Long.parseLong(nextToken());
	}

	private float nextFloat() throws IOException {
		return Float.parseFloat(nextToken());
	}

	private String nextLine() throws IOException {
		return new String(in.readLine());
	}

	private String nextToken() throws IOException {
		while (tokenizer == null || !tokenizer.hasMoreTokens()) {
			tokenizer = new StringTokenizer(in.readLine());
		}
		return tokenizer.nextToken();
	}
}

class Edge{
	int u;
	int v;
	long w;
	

	@Override
	public int hashCode() {
		final int prime = 31;
		int result = 1;
		result = prime * result + u;
		result = prime * result + v;
		return result;
	}

	@Override
	public boolean equals(Object obj) {
		if (this == obj)
			return true;
		if (obj == null)
			return false;
		if (getClass() != obj.getClass())
			return false;
		Edge other = (Edge) obj;
		if (u != other.u)
			return false;
		if (v != other.v)
			return false;
		return true;
	}

	
	public Edge(int u, int v){
		this.u = Math.min(u, v);
		this.v = Math.max(u, v);
		this.w = 0L;
	}
	
	public int other(int u){
		if(this.u == u) return this.v;
		else return this.u;
	}
	
	public void add(long s){
		this.w += s;
	}
	
	
}