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 = 1e5 + 10;
int N, M;
long long C[MAXN], csum[MAXN];
int A[MAXN], B[MAXN];
map<int, int> mpid[MAXN];
vector<int> adj[MAXN];
int par[MAXN];
int ord[MAXN], cord;
int col[MAXN];
int odde = -1;
long long ans[MAXN];
void addedge(int id, long long w) {
  ;
  ans[id] += w;
  csum[A[id]] -= w;
  csum[B[id]] -= w;
}
void addedge(int a, int b, long long w) { addedge(mpid[a][b], w); }
void printans() {
  for (int i = 1; i <= N; i++) {
    assert(csum[i] == 0);
  }
  puts("YES");
  for (int i = 1; i <= M; i++) {
    printf("%lld\n", ans[i]);
  }
  exit(0);
}
vector<int> ocyc;
void dfs(int x, int c, bool newcyc) {
  col[x] = c;
  ord[x] = ++cord;
  for (int y : adj[x]) {
    if (y == par[x]) {
      continue;
    }
    if (ord[y] != 0) {
      if (ord[y] < ord[x]) {
        if (newcyc && odde == -1 && col[y] == c) {
          odde = mpid[x][y];
          for (int i = x;; i = par[i]) {
            ocyc.push_back(i);
            if (i == y) {
              break;
            }
          }
        }
      }
    } else {
      par[y] = x;
      dfs(y, !c, newcyc);
      addedge(x, y, csum[y]);
    }
  }
}
int main() {
  scanf("%d %d", &N, &M);
  for (int i = 1; i <= N; i++) {
    scanf("%lld", &C[i]);
    csum[i] = C[i];
  }
  for (int i = 1; i <= M; i++) {
    int a, b;
    scanf("%d %d", &a, &b);
    mpid[a][b] = mpid[b][a] = i;
    adj[a].push_back(b);
    adj[b].push_back(a);
    A[i] = a;
    B[i] = b;
  }
  memset(col, -1, sizeof(col));
  dfs(1, 0, true);
  if (odde == -1) {
    if (csum[1]) {
      puts("NO");
      return 0;
    }
    printans();
  };
  cord = 0;
  for (int i = 1; i <= max(N, M); i++) {
    csum[i] = C[i];
    par[i] = 0;
    ord[i] = 0;
    col[i] = -1;
    ans[i] = 0;
  }
  int root = A[odde];
  ;
  dfs(root, 0, false);
  ;
  rotate(ocyc.begin(), find((ocyc).begin(), (ocyc).end(), root), ocyc.end());
  long long val = csum[root] / 2;
  ;
  for (int i = 0, sgn = 1; i < ocyc.size(); i++, sgn *= -1) {
    ;
    addedge(ocyc[i], ocyc[(i + 1) % ocyc.size()], sgn * val);
  }
  printans();
}
