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;
const int N = 200000;
int col[N], di[N];
long long ai[N];
int A[N], B[N], V[N], P[N];
long long S[N];
vector<int> edge[N];
int L;
queue<int> Q;
void dfs(int t, int c) {
  col[t] = c;
  for (int i = 0; i < edge[t].size(); ++i) {
    int b = A[edge[t][i]] + B[edge[t][i]] - t;
    if (col[b] == -1)
      dfs(b, !c);
    else if (col[b] == col[t])
      L = edge[t][i];
  }
}
int fa[N];
int get_f(int t) { return fa[t] = (fa[t] == t ? t : get_f(fa[t])); }
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= n; ++i) scanf("%d", &ai[i]);
  for (int i = 1; i <= m; ++i) {
    scanf("%d%d", &A[i], &B[i]);
    edge[A[i]].push_back(i);
    di[A[i]]++;
    edge[B[i]].push_back(i);
    di[B[i]]++;
  }
  for (int i = 1; i <= n; ++i) col[i] = -1;
  dfs(1, 0);
  if (L) {
    for (int i = 1; i <= n; ++i) fa[i] = i;
    V[L] = 1;
    for (int i = 1; i <= m; ++i)
      if (i != L)
        if (get_f(A[i]) != get_f(B[i]) && col[A[i]] != col[B[i]])
          V[i] = 1, fa[get_f(A[i])] = get_f(B[i]);
    for (int i = 1; i <= m; ++i)
      if (!V[i]) {
        S[i] = 1;
        di[A[i]]--;
        di[B[i]]--;
        ai[A[i]]--;
        ai[B[i]]--;
      }
    for (int i = 1; i <= n; ++i)
      if (di[i] == 1) Q.push(i);
    while (!Q.empty()) {
      int t = Q.front();
      Q.pop();
      for (int i = 0; i < edge[t].size(); ++i)
        if (V[edge[t][i]]) {
          int b = A[edge[t][i]] + B[edge[t][i]] - t;
          if (!di[b]) continue;
          di[t]--;
          di[b]--;
          S[edge[t][i]] = ai[t];
          ai[b] -= ai[t];
          ai[t] = 0;
          if (di[b] == 1) Q.push(b);
        }
    }
    int start = -1;
    for (int i = 1; i <= n; ++i)
      if (di[i] && start == -1) start = i;
    int p = start;
    long long sum = ai[p], k = 1;
    for (int i = 0; i < edge[p].size(); ++i)
      if (V[edge[p][i]]) {
        int q = A[edge[p][i]] + B[edge[p][i]] - p;
        if (di[q]) {
          p = q;
          break;
        }
      }
    for (int o = start; p != start;) {
      sum += k * ai[p];
      for (int i = 0; i < edge[p].size(); ++i)
        if (V[edge[p][i]]) {
          int q = A[edge[p][i]] + B[edge[p][i]] - p;
          if (di[q] && q != o) {
            o = p;
            p = q;
            k *= -1;
            break;
          }
        }
    }
    p = start;
    ai[p] -= sum / 2;
    for (int i = 0; i < edge[p].size(); ++i)
      if (V[edge[p][i]]) {
        int q = A[edge[p][i]] + B[edge[p][i]] - p;
        if (di[q]) {
          S[edge[p][i]] = sum / 2;
          ai[q] -= sum / 2;
          p = q;
          break;
        }
      }
    for (int o = start; p != start;) {
      for (int i = 0; i < edge[p].size(); ++i)
        if (V[edge[p][i]]) {
          int q = A[edge[p][i]] + B[edge[p][i]] - p;
          if (di[q] && q != o) {
            S[edge[p][i]] = ai[p];
            ai[q] -= ai[p];
            o = p;
            p = q;
            break;
          }
        }
    }
    puts("YES");
    for (int i = 1; i <= m; ++i) printf("%lld\n", S[i]);
  } else {
    for (int i = 1; i <= n; ++i) fa[i] = i;
    for (int i = 1; i <= m; ++i)
      if (get_f(A[i]) != get_f(B[i]) && col[A[i]] != col[B[i]])
        V[i] = 1, fa[get_f(A[i])] = get_f(B[i]);
    for (int i = 1; i <= m; ++i)
      if (!V[i]) {
        S[i] = 1;
        di[A[i]]--;
        di[B[i]]--;
        ai[A[i]]--;
        ai[B[i]]--;
      }
    for (int i = 1; i <= n; ++i)
      if (di[i] == 1) Q.push(i);
    while (!Q.empty()) {
      int t = Q.front();
      Q.pop();
      for (int i = 0; i < edge[t].size(); ++i)
        if (V[edge[t][i]]) {
          int b = A[edge[t][i]] + B[edge[t][i]] - t;
          if (!di[b]) continue;
          di[t]--;
          di[b]--;
          S[edge[t][i]] = ai[t];
          ai[b] -= ai[t];
          ai[t] = 0;
          if (!di[b] && ai[b]) {
            puts("NO");
            exit(0);
          }
          if (di[b] == 1) Q.push(b);
        }
    }
    puts("YES");
    for (int i = 1; i <= m; ++i) printf("%lld\n", S[i]);
  }
}
