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, col[100005];
long long sum[2], num[100005];
bool ex[2];
vector<int> edge[100005];
void dfs(int v, int c) {
  if (col[v] != -1) return;
  col[v] = c;
  sum[c] += num[v];
  for (int i = 0; i < edge[v].size(); i++) {
    if (col[edge[v][i]] == -1)
      dfs(edge[v][i], 1 - c);
    else if (col[edge[v][i]] == c) {
      ex[c] = 1;
    }
  }
}
pair<int, int> zip[100050];
map<pair<int, int>, long long> val;
int par[100005], ran[100005];
void init() {
  for (int i = 0; i < 100005; i++) par[i] = i;
}
int find(int x) {
  if (x == par[x])
    return x;
  else
    return par[x] = find(par[x]);
}
void unite(int x, int y) {
  x = find(x);
  y = find(y);
  if (x == y) return;
  if (ran[x] < ran[y])
    par[x] = y;
  else {
    par[y] = x;
    if (ran[x] == ran[y]) ran[x]++;
  }
}
bool same(int x, int y) { return find(x) == find(y); }
vector<int> G[100005];
long long DFS(int v, int u) {
  long long V = num[v];
  for (int i = 0; i < G[v].size(); i++) {
    if (G[v][i] == u) continue;
    V -= DFS(G[v][i], v);
  }
  if (u == -1)
    assert(V == 0LL);
  else {
    val[make_pair(v, u)] = val[make_pair(u, v)] = V;
  }
  return V;
}
int main() {
  cin >> n >> m;
  for (int i = 1; i <= n; i++) cin >> num[i];
  init();
  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    zip[i] = make_pair(a, b);
    edge[a].push_back(b);
    edge[b].push_back(a);
  }
  memset(col, -1, sizeof(col));
  dfs(1, 0);
  if (sum[0] != sum[1] && !ex[0] && !ex[1]) {
    puts("NO");
    return 0;
  }
  puts("YES");
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j < edge[i].size(); j++) {
      if (i > edge[i][j]) continue;
      if (col[i] != col[edge[i][j]]) {
        continue;
      }
      long long hoge = sum[col[i]] - sum[1 - col[i]];
      hoge /= 2;
      val[make_pair(i, edge[i][j])] = val[make_pair(edge[i][j], i)] = hoge;
      num[i] -= hoge;
      num[edge[i][j]] -= hoge;
      goto nxt;
    }
  }
nxt:;
  for (int i = 1; i <= n; i++) {
    for (int j = 0; j < edge[i].size(); j++) {
      if (i > edge[i][j]) continue;
      if (col[i] != col[edge[i][j]]) {
        int a = i, b = edge[i][j];
        if (!same(a, b)) {
          G[a].push_back(b);
          G[b].push_back(a);
          unite(a, b);
        }
        continue;
      }
    }
  }
  DFS(1, -1);
  for (int i = 0; i < m; i++) printf("%lld\n", val[zip[i]]);
}
