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

#include <bits/stdc++.h>
#pragma GCC optimize(2)
#pragma GCC optimize(3)
#pragma GCC optimize("Ofast")
using namespace std;
inline int get() {
  int n = 0;
  char c;
  while ((c = getchar()) || 23333) {
    if (c >= '0' && c <= '9') break;
    if (c == '-') goto s;
  }
  n = c - '0';
  while ((c = getchar()) || 23333) {
    if (c >= '0' && c <= '9')
      n = n * 10 + c - '0';
    else
      return (n);
  }
s:
  while ((c = getchar()) || 23333) {
    if (c >= '0' && c <= '9')
      n = n * 10 - c + '0';
    else
      return (n);
  }
}
typedef struct _b {
  int dest;
  int nxt;
  int num;
} bian;
bian memchi[200001];
int gn = 1;
int heads[200001], ints[100001], anss[100001], ss[100001], ts[100001],
    v[100001];
inline void add(int s, int t, int num) {
  memchi[gn].dest = t;
  memchi[gn].nxt = heads[s];
  memchi[gn].num = num;
  heads[s] = gn;
  gn++;
}
unsigned char col[100001];
int que[100001];
unsigned char istree[100001];
void print(int num) {
  if (num < 0) putchar('-'), num = -num;
  if (num >= 10) print(num / 10);
  putchar(num % 10 + '0');
}
int find(int n) {
  if (ints[n] == n) return (n);
  return (ints[n] = find(ints[n]));
}
void dfs(int pt, int baba) {
  for (register int i = heads[pt]; i; i = memchi[i].nxt) {
    if (memchi[i].dest == baba) continue;
    dfs(memchi[i].dest, pt);
    anss[memchi[i].num] += v[memchi[i].dest];
    v[pt] -= v[memchi[i].dest];
    v[memchi[i].dest] = 0;
  }
}
int tmp[100001];
void efs(int pt, int baba) {
  for (register int i = heads[pt]; i; i = memchi[i].nxt) {
    if (memchi[i].dest == baba) continue;
    efs(memchi[i].dest, pt);
    tmp[pt] -= tmp[memchi[i].dest];
  }
}
int main() {
  int n = get(), m = get();
  for (register int i = 1; i <= n; i++) v[i] = get(), ints[i] = i, col[i] = 2;
  for (register int i = 1; i <= m; i++) {
    ss[i] = get(), ts[i] = get();
    int aa = find(ss[i]), ab = find(ts[i]);
    if (aa != ab) {
      ints[aa] = ab;
      add(ss[i], ts[i], i);
      add(ts[i], ss[i], i);
      istree[i] = 1;
    }
  }
  register int head = 0, tail = 1;
  que[0] = 1;
  col[1] = 0;
  do {
    int me = que[head];
    head++;
    for (register int i = heads[me]; i; i = memchi[i].nxt) {
      if (col[memchi[i].dest] != 2) continue;
      col[memchi[i].dest] = col[me] ^ 1;
      que[tail] = memchi[i].dest;
      tail++;
    }
  } while (head < tail);
  dfs(1, 0);
  if (((v[1] < 0) ? -(v[1]) : v[1]) & 1) {
    printf("NO\n");
    return (0);
  }
  for (register int a = 1; a <= m; a++) {
    if (istree[a]) continue;
    if (col[ss[a]] != col[ts[a]]) continue;
    printf("YES\n");
    int val = v[1] / 2;
    tmp[ss[a]]++;
    tmp[ts[a]]++;
    efs(1, 0);
    if (tmp[1] == 2) {
      v[ss[a]] -= val;
      v[ts[a]] -= val;
      anss[a] = val;
    } else {
      v[ss[a]] += val;
      v[ts[a]] += val;
      anss[a] = -val;
    }
    dfs(1, 0);
    for (register int i = 1; i <= m; i++) print(anss[i]), putchar('\n');
    return (0);
  }
  if (v[1] == 0) {
    printf("YES\n");
    for (register int i = 1; i <= m; i++) print(anss[i]), putchar('\n');
    return (0);
  }
  printf("NO\n");
  return (0);
}
