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 n, m, tot;
int u[200005], v[200005], on_tree[200005], fa[200005], col[200005],
    fath[200005], dep[200005];
long long c[200005], mk[200005];
vector<int> G[200005];
unordered_map<int, unordered_map<int, long long> > val;
inline int read() {
  int x = 0, f = 1;
  char ch = getchar();
  while (!isdigit(ch)) {
    if (ch == '-') f = -1;
    ch = getchar();
  }
  while (isdigit(ch)) {
    (x *= 10) += ch - '0';
    ch = getchar();
  }
  return x * f;
}
inline void add_edge(int u, int v) {
  G[u].push_back(v);
  G[v].push_back(u);
}
int findf(int x) { return x == fa[x] ? x : fa[x] = findf(fa[x]); }
void kruskal() {
  for (int i = 1; i <= n; i++) fa[i] = i;
  for (int i = 1; i <= m; i++) {
    if (tot == n - 1) return;
    int uf = findf(u[i]), vf = findf(v[i]);
    if (uf == vf) continue;
    on_tree[i] = 1;
    add_edge(u[i], v[i]);
    tot++;
    fa[uf] = vf;
  }
}
void dfs1(int u, int c_fa, int c_col) {
  col[u] = c_col;
  fath[u] = c_fa;
  dep[u] = dep[c_fa] + 1;
  for (int v : G[u]) {
    if (v == c_fa) continue;
    dfs1(v, u, c_col ^ 1);
    c[u] -= val[u][v];
  }
  val[u][c_fa] = val[c_fa][u] = c[u];
}
void work(int _x, int _y) {
  int x = _x, y = _y;
  int dis = 0, delta = 0, flag = -1;
  if (dep[x] < dep[y]) swap(x, y);
  while (dep[x] > dep[1]) dis++, x = fath[x];
  if (dis & 1)
    delta = -c[1] / 2;
  else
    delta = c[1] / 2;
  x = _x, y = _y;
  if (dep[x] < dep[y]) swap(x, y);
  while (dep[x] > dep[y]) {
    val[x][fath[x]] += flag * delta, val[fath[x]][x] += flag * delta;
    flag = -flag, x = fath[x];
  }
  while (dep[x] > dep[1]) {
    val[x][fath[x]] += flag * delta, val[fath[x]][x] += flag * delta;
    val[y][fath[y]] += flag * delta, val[fath[y]][y] += flag * delta;
    flag = -flag, x = fath[x], y = fath[y];
  }
  val[_x][_y] = val[_y][_x] = delta;
}
int main() {
  n = read(), m = read();
  for (int i = 1; i <= n; i++) c[i] = read();
  for (int i = 1; i <= m; i++) u[i] = read(), v[i] = read();
  kruskal();
  dfs1(1, 0, 1);
  if (c[1] == 0) {
    puts("YES");
    for (int i = 1; i <= m; i++) printf("%lld\n", val[u[i]][v[i]]);
    return 0;
  }
  if (c[1] & 1) {
    puts("NO");
    return 0;
  }
  for (int i = 1; i <= m; i++) {
    if (col[u[i]] != col[v[i]] || on_tree[i]) continue;
    puts("YES");
    work(u[i], v[i]);
    for (int i = 1; i <= m; i++) printf("%lld\n", val[u[i]][v[i]]);
    return 0;
  }
  puts("NO");
  return 0;
}
