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 = 100005;
struct edge {
  int u, v, index;
};
int n, m, c[MAXN];
vector<edge> g[MAXN];
edge c_edge, p_edge[MAXN];
int s[2], color[MAXN], p[MAXN], w[MAXN];
void dfs(int u) {
  if (p[u] == -1)
    color[u] = 0;
  else
    color[u] = color[p[u]] ^ 1;
  s[color[u]] += c[u];
  for (edge e : g[u]) {
    int v = e.u ^ e.v ^ u;
    if (color[v] == -1) {
      p[v] = u;
      p_edge[v] = e;
      dfs(v);
    } else {
      if (color[u] == color[v] && c_edge.index == -1) c_edge = e;
    }
  }
}
bool vis[MAXN];
void calc(int u) {
  vis[u] = true;
  for (edge e : g[u]) {
    int v = e.u ^ e.v ^ u;
    if (!vis[v]) calc(v);
  }
  if (c[u] != 0) {
    w[p_edge[u].index] += c[u];
    c[p_edge[u].u] -= w[p_edge[u].index];
    c[p_edge[u].v] -= w[p_edge[u].index];
  }
}
int main() {
  scanf("%d %d", &n, &m);
  for (int i = 0; i < n; i++) scanf("%d", &c[i]);
  for (int i = 0; i < m; i++) {
    edge e;
    scanf("%d %d", &e.u, &e.v);
    e.u--, e.v--;
    e.index = i;
    g[e.u].push_back(e);
    g[e.v].push_back(e);
  }
  memset(color, -1, sizeof color);
  memset(p, -1, sizeof p);
  bool ok = true;
  for (int i = 0; i < n; i++)
    if (color[i] == -1) {
      s[0] = 0, s[1] = 0;
      c_edge.index = -1;
      dfs(i);
      if (s[0] != s[1] && c_edge.index == -1) {
        ok = false;
        break;
      } else {
        if (s[0] != s[1]) {
          if (color[c_edge.u] == 0) {
            w[c_edge.index] += (s[0] - s[1]) / 2;
            c[c_edge.u] -= w[c_edge.index];
            c[c_edge.v] -= w[c_edge.index];
          } else {
            w[c_edge.index] += (s[1] - s[0]) / 2;
            c[c_edge.u] -= w[c_edge.index];
            c[c_edge.v] -= w[c_edge.index];
          }
        }
        calc(i);
      }
    }
  if (ok) {
    printf("YES\n");
    for (int i = 0; i < m; i++) printf("%d\n", w[i]);
  } else {
    printf("NO\n");
  }
  return 0;
}
