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.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Div1_453D {

	static int[] val;

	static ArrayList<Integer>[] aList;
	static ArrayList<Integer>[] eList;

	static int[] color;

	static int[] pV;
	static int[] pE;

	static int cStart;
	static int cEnd;
	static int cEdge;

	static int[] ans;

	static boolean[] visited;

	public static void main(String[] args) throws IOException {
		BufferedReader reader = new BufferedReader(new InputStreamReader(System.in));
		PrintWriter printer = new PrintWriter(new BufferedWriter(new OutputStreamWriter(System.out)));
		StringTokenizer inputData = new StringTokenizer(reader.readLine());
		int nV = Integer.parseInt(inputData.nextToken());
		int nE = Integer.parseInt(inputData.nextToken());
		val = new int[nV];
		inputData = new StringTokenizer(reader.readLine());
		for (int i = 0; i < nV; i++) {
			val[i] = Integer.parseInt(inputData.nextToken());
		}

		aList = new ArrayList[nV];
		eList = new ArrayList[nV];
		for (int i = 0; i < nV; i++) {
			aList[i] = new ArrayList<>();
			eList[i] = new ArrayList<>();
		}
		for (int i = 0; i < nE; i++) {
			inputData = new StringTokenizer(reader.readLine());
			int a = Integer.parseInt(inputData.nextToken()) - 1;
			int b = Integer.parseInt(inputData.nextToken()) - 1;
			aList[a].add(b);
			aList[b].add(a);
			eList[a].add(i);
			eList[b].add(i);
		}

		color = new int[nV];
		Arrays.fill(color, -1);

		pV = new int[nV];
		pE = new int[nV];

		color[0] = 0;
		boolean isBipartite = color(0);

		ans = new int[nV];

		visited = new boolean[nV];
		if (isBipartite) {
			gDetermine(0);
			if (val[0] == 0) {
				printer.println("Yes");
				for (int i = 0; i < nE; i++) {
					printer.println(-ans[i]);
				}
			} else {
				printer.println("NO");
			}
		} else {
			gDetermine(cEnd);
			int delta = -val[cEnd] / 2;
			int cV = cEnd;
			while (cV != cStart) {
				ans[pE[cV]] += delta;
				cV = pV[cV];
				delta = -delta;
			}
			ans[cEdge] += delta;
			printer.println("YES");
			for (int i = 0; i < nE; i++) {
				printer.println(-ans[i]);
			}
		}
		printer.close();
	}

	static boolean color(int cV) {
		for (int aI = 0; aI < aList[cV].size(); aI++) {
			int aV = aList[cV].get(aI);
			int aE = eList[cV].get(aI);
			if (color[aV] == -1) {
				color[aV] = color[cV] ^ 1;
				pV[aV] = cV;
				pE[aV] = aE;
				if(!color(aV)) {
					return false;
				}
			} else {
				if (color[aV] == color[cV]) {
					cEnd = cV;
					cStart = aV;
					cEdge = aE;
					return false;
				}
			}
		}
		return true;
	}

	static void gDetermine(int cV) {
		visited[cV] = true;
		for (int aI = 0; aI < aList[cV].size(); aI++) {
			int aV = aList[cV].get(aI);
			int eI = eList[cV].get(aI);
			if (!visited[aV]) {
				gDetermine(aV);
				ans[eI] = -val[aV];
				val[cV] -= val[aV];
				val[aV] = 0;
			}
		}
	}

}
