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>
using namespace std;
const int Maxn = 100010;
const int inf = 2147483647;
int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9')
    x = (x << 3) + (x << 1) + (ch ^ 48), ch = getchar();
  return x * f;
}
int n, m, t, a[Maxn], dep[Maxn];
bool vis[Maxn], mark[Maxn << 1];
struct Edge {
  int x, y, d, next;
} e[Maxn << 1];
int last[Maxn], len = 1;
void ins(int x, int y) {
  int t = ++len;
  e[t].x = x;
  e[t].y = y;
  e[t].next = last[x];
  last[x] = t;
}
void dfs(int x, int fa, int id) {
  dep[x] = dep[fa] + 1;
  vis[x] = true;
  int s = 0;
  for (int i = last[x]; i; i = e[i].next) {
    int y = e[i].y;
    if (vis[y]) continue;
    mark[i] = mark[i ^ 1] = true;
    dfs(y, x, i);
    s += e[i].d;
  }
  if (id)
    e[id].d = e[id ^ 1].d = a[x] - s;
  else
    t = s;
}
void DFS(int x, int id) {
  vis[x] = true;
  int s = 0;
  for (int i = last[x]; i; i = e[i].next) {
    int y = e[i].y;
    if (vis[y]) {
      if (i != (id ^ 1)) s += e[i].d;
      continue;
    }
    DFS(y, i);
    s += e[i].d;
  }
  if (id) e[id].d = e[id ^ 1].d = a[x] - s;
}
int main() {
  n = read(), m = read();
  for (int i = 1; i <= n; i++) a[i] = read();
  for (int i = 1; i <= m; i++) {
    int x = read(), y = read();
    ins(x, y), ins(y, x);
  }
  dep[0] = -1;
  dfs(1, 0, 0);
  int cnt = 0;
  for (int i = 2; i <= len; i += 2)
    if (mark[i])
      continue;
    else if (!(abs(dep[e[i].x] - dep[e[i].y]) & 1)) {
      cnt++;
      break;
    }
  if (abs(t - a[1]) % 2) return puts("NO"), 0;
  if (!cnt && a[1] != t) return puts("NO"), 0;
  puts("YES");
  if (a[1] == t) {
    for (int i = 2; i <= len; i += 2) {
      if (mark[i])
        printf("%d\n", e[i].d);
      else
        puts("0");
    }
    return 0;
  }
  for (int i = 2; i <= len; i += 2)
    if (!(abs(dep[e[i].x] - dep[e[i].y]) & 1)) {
      int x = e[i].x, y = e[i].y;
      if (a[1] > t) {
        if (dep[x] > dep[y]) swap(x, y);
        if (dep[x] & 1)
          e[i].d = e[i ^ 1].d = -abs(t - a[1]) / 2;
        else
          e[i].d = e[i ^ 1].d = abs(t - a[1]) / 2;
      } else {
        if (dep[x] > dep[y]) swap(x, y);
        if (dep[x] & 1)
          e[i].d = e[i ^ 1].d = abs(t - a[1]) / 2;
        else
          e[i].d = e[i ^ 1].d = -abs(t - a[1]) / 2;
      }
      break;
    }
  memset(vis, false, sizeof(vis));
  DFS(1, 0);
  for (int i = 2; i <= len; i += 2) printf("%d\n", e[i].d);
}
