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;
int read() {
  int x = 0;
  bool flg = false;
  char ch = getchar();
  for (; !isdigit(ch); ch = getchar())
    if (ch == '-') flg = true;
  for (; isdigit(ch); ch = getchar()) x = (x << 3) + (x << 1) + (ch ^ 48);
  return flg ? -x : x;
}
int n, m;
long long w[100010], cw[100010];
struct Rec {
  int u, v;
  bool mrk;
  long long ans;
} rec[100010];
struct Edge {
  int to, nxt, id;
} edge[200010];
int cnt = 1, last[100010];
inline void addedge(int x, int y, int id) {
  edge[++cnt] = (Edge){y, last[x], id}, last[x] = cnt;
  edge[++cnt] = (Edge){x, last[y], id}, last[y] = cnt;
}
namespace B {
int f[100010];
int find(int x) { return f[x] ? f[x] = find(f[x]) : x; }
}  // namespace B
int fat[100010], son[100010], dep[100010], siz[100010];
int top[100010];
void dfs1(int cur, int fat, int dep) {
  ::fat[cur] = fat;
  ::dep[cur] = dep;
  siz[cur] = 1;
  for (int i = last[cur]; i; i = edge[i].nxt)
    if (edge[i].to ^ fat) {
      dfs1(edge[i].to, cur, dep + 1);
      rec[edge[i].id].ans = w[edge[i].to] - cw[edge[i].to];
      cw[cur] += rec[edge[i].id].ans;
      siz[cur] += siz[edge[i].to];
      if (!son[cur] || siz[edge[i].to] > siz[son[cur]]) son[cur] = edge[i].to;
    }
}
void dfs2(int cur, int top) {
  ::top[cur] = top;
  if (siz[cur] == 1) return;
  dfs2(son[cur], top);
  for (int i = last[cur]; i; i = edge[i].nxt)
    if ((edge[i].to ^ fat[cur]) && (edge[i].to ^ son[cur]))
      dfs2(edge[i].to, edge[i].to);
}
void dfs3(int cur) {
  for (int i = last[cur]; i; i = edge[i].nxt)
    if (edge[i].to ^ fat[cur]) {
      dfs3(edge[i].to);
      rec[edge[i].id].ans = w[edge[i].to] - cw[edge[i].to];
      cw[cur] += rec[edge[i].id].ans;
    }
}
int getlca(int x, int y) {
  while (top[x] ^ top[y])
    if (dep[top[x]] < dep[top[y]])
      y = fat[top[y]];
    else
      x = fat[top[x]];
  if (dep[x] < dep[y]) return x;
  return y;
}
int getdis(int x, int y) { return dep[x] + dep[y] - (dep[getlca(x, y)] << 1); }
int main() {
  n = read(), m = read();
  for (int i = 1; i <= n; i++) w[i] = read();
  for (int i = 1, x, y; i <= m; i++) {
    rec[i].u = read(), rec[i].v = read();
    x = B::find(rec[i].u), y = B::find(rec[i].v);
    if (x ^ y) rec[i].mrk = true, addedge(rec[i].u, rec[i].v, i), B::f[y] = x;
  }
  dfs1(1, 0, 1);
  if (w[1] == cw[1]) {
    puts("YES");
    for (int i = 1; i <= m; i++) printf("%lld\n", rec[i].ans);
    return 0;
  }
  dfs2(1, 1);
  long long tmp = w[1] - cw[1];
  for (int i = 1; i <= m; i++) rec[i].ans = 0;
  for (int i = 1; i <= n; i++) cw[i] = 0;
  bool flg = false;
  for (int i = 1; i <= m; i++) {
    if (rec[i].mrk) continue;
    if (!(getdis(rec[i].u, rec[i].v) & 1)) {
      if (dep[rec[i].u] & 1)
        cw[rec[i].u] = cw[rec[i].v] = rec[i].ans = tmp / 2;
      else
        cw[rec[i].u] = cw[rec[i].v] = rec[i].ans = -tmp / 2;
      flg = true;
      break;
    }
  }
  if (!flg) return puts("NO"), 0;
  puts("YES");
  dfs3(1);
  for (int i = 1; i <= m; i++) printf("%lld\n", rec[i].ans);
  return 0;
}
