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 + 5;
int n, m;
long long arr[N];
int a[N], b[N];
vector<int> v[N];
long long ans[N];
bool visited[N];
vector<int> cycle;
int parent[N];
int depth[N];
int who[N];
void dfs(int node) {
  for (int edge : v[node]) {
    int next = a[edge] ^ b[edge] ^ node;
    if (visited[next]) {
      continue;
    }
    visited[next] = 1;
    parent[next] = edge;
    depth[next] = depth[node] + 1;
    if (node == 1) {
      who[next] == next;
    } else {
      who[next] = who[node];
    }
    dfs(next);
    ans[edge] = arr[next];
    arr[next] -= ans[edge];
    arr[node] -= ans[edge];
  }
}
vector<int> x, y;
void get(int a, int b, int i) {
  long long add = arr[1] / 2;
  while (a != 1) {
    int edge = parent[a];
    x.emplace_back(edge);
    a = ::a[edge] ^ ::b[edge] ^ a;
  }
  while (b != 1) {
    int edge = parent[b];
    y.emplace_back(edge);
    b = ::a[edge] ^ ::b[edge] ^ b;
  }
  reverse(y.begin(), y.end());
  for (int edge : y) {
    ans[edge] += add;
    add *= -1;
  }
  ans[i] += add;
  add *= -1;
  for (int edge : x) {
    ans[edge] += add;
    add *= -1;
  }
  arr[1] = 0;
}
void fix() {
  for (int i = 1; i <= m; ++i) {
    if (parent[a[i]] == b[i] || parent[b[i]] == a[i]) {
      continue;
    }
    if (a[i] == 1 || b[i] == 1 || who[a[i]] != who[b[i]]) {
      if ((depth[a[i]] & 1) == (depth[b[i]] & 1)) {
        get(a[i], b[i], i);
        break;
      } else {
        continue;
      }
    } else {
      continue;
    }
  }
}
int main() {
  scanf("%d %d", &n, &m);
  for (int i = 1; i <= n; ++i) {
    scanf("%lld", arr + i);
  }
  for (int i = 1; i <= m; ++i) {
    scanf("%d %d", a + i, b + i);
    v[a[i]].emplace_back(i);
    v[b[i]].emplace_back(i);
  }
  visited[1] = 1;
  dfs(1);
  fix();
  if (arr[1]) {
    printf("NO\n");
  } else {
    printf("YES\n");
    for (int i = 1; i <= m; ++i) {
      printf("%lld\n", ans[i]);
    }
  }
}
