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 N = 1e5 + 10;
int head[N], nxt[N << 1], to[N << 1], E;
long long ans[N];
long long val[N];
int vst[N], dep[N];
int fa[N];
vector<int> path;
void dfs(int u) {
  for (int e = head[u]; ~e && path.empty(); e = nxt[e]) {
    int v = to[e];
    if (vst[v]) {
      if (vst[v] == vst[u]) {
        int U = u, V = v;
        while (dep[U] > dep[V]) {
          path.push_back(U);
          U = fa[U];
        }
        stack<int> a;
        while (dep[V] > dep[U]) {
          a.push(V);
          V = fa[V];
        }
        while (true) {
          path.push_back(U);
          if (U != V) {
            a.push(V);
          }
          U = fa[U];
          V = fa[V];
          break;
        }
        while (!a.empty()) {
          path.push_back(a.top());
          a.pop();
        }
      }
    } else {
      vst[v] = vst[u] ^ 1;
      fa[v] = u;
      dep[v] = dep[u] + 1;
      dfs(v);
    }
  }
}
void rdfs(int u) {
  vst[u] = 1;
  for (int e = head[u]; ~e; e = nxt[e]) {
    int v = to[e];
    if (vst[v]) {
      continue;
    }
    rdfs(v);
    ans[e >> 1] = val[v];
    val[u] -= val[v];
  }
}
int main() {
  memset(head, -1, sizeof head);
  int n, m;
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= n; i++) {
    scanf("%I64d", val + i);
  }
  for (int i = 0; i < m; i++) {
    int u, v;
    scanf("%d %d", &u, &v);
    nxt[E] = head[u];
    to[E] = v;
    head[u] = E++;
    nxt[E] = head[v];
    to[E] = u;
    head[v] = E++;
  }
  vst[1] = 2;
  dfs(1);
  memset(vst, 0, sizeof vst);
  if (path.empty()) {
    rdfs(1);
    if (val[1]) {
      puts("NO");
      return 0;
    }
  } else {
    for (auto u : path) {
      vst[u] = 2;
    }
    long long tot = 0;
    long long crr = 0;
    for (int i = 0; i < path.size(); i++) {
      rdfs(path[i]);
      tot += val[path[i]];
      if (i > 1 && !(i & 1)) {
        crr += val[path[i]];
      }
    }
    if (tot & 1) {
      puts("NO");
      return 0;
    }
    tot >>= 1;
    for (int i = 0; i < path.size(); i++) {
      int u = path[i];
      int v = i + 1 < path.size() ? path[i + 1] : path[0];
      for (int e = head[u]; ~e; e = nxt[e]) {
        if (to[e] == v) {
          ans[e >> 1] = tot - crr;
          break;
        }
      }
      crr = tot * 2 - crr - val[v];
    }
  }
  puts("YES");
  for (int i = 0; i < m; i++) {
    printf("%I64d\n", ans[i]);
  }
  return 0;
}
