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;
vector<pair<int, int> > G[100005];
int Colour[100005], Stack[100005], P[100005], top;
pair<int, int> E[100005];
bool bipartite = 1;
long long Res[100005], C[100005];
vector<int> Cycle;
int Level[100005];
bool Use[100005];
map<pair<int, int>, int> Map;
void Read() {
  cin >> N >> M;
  for (int i = 1; i <= N; i++) cin >> C[i];
  for (int i = 1; i <= M; i++) {
    int x, y;
    cin >> x >> y;
    Map[make_pair(min(x, y), max(x, y))] = i;
    E[i] = make_pair(x, y);
    G[x].push_back(make_pair(y, i));
    G[y].push_back(make_pair(x, i));
  }
}
void DFS(int node, int colour) {
  Colour[node] = colour;
  for (int i = 0; i < G[node].size(); i++) {
    int neighb = G[node][i].first;
    if (Colour[neighb] == 0)
      DFS(neighb, 3 - colour);
    else {
      if (Colour[neighb] == Colour[node]) bipartite = 0;
    }
  }
}
void SolveCase1(int node, int father, int edge) {
  long long sum = 0;
  Use[node] = 1;
  for (int i = 0; i < G[node].size(); i++) {
    int neighb = G[node][i].first, e = G[node][i].second;
    if (neighb == father) continue;
    if (Use[neighb] == 1) continue;
    SolveCase1(neighb, node, e);
    sum += Res[e];
  }
  Res[edge] = C[node] - sum;
}
void findCycle(int node, int father) {
  Use[node] = 1;
  Level[node] = Level[father] + 1;
  Stack[++top] = node;
  P[node] = top;
  for (int i = 0; i < G[node].size(); i++) {
    int neighb = G[node][i].first, e = G[node][i].second;
    if (neighb == father) continue;
    if (Cycle.size() == 0 && Use[neighb] == 1 && Level[neighb] < Level[node] &&
        (Level[node] - Level[neighb] + 1) % 2 == 1) {
      for (int j = P[neighb]; j <= top; j++) Cycle.push_back(Stack[j]);
    }
    if (Use[neighb] == 0) findCycle(neighb, node);
  }
  --top;
}
void SolveCase2(int node, int father, int edge) {
  long long sum = 0;
  Use[node] = 1;
  for (int i = 0; i < G[node].size(); i++) {
    int neighb = G[node][i].first, e = G[node][i].second;
    if (neighb == father) continue;
    if (Use[neighb] == 1) continue;
    SolveCase2(neighb, node, e);
    sum += Res[e];
  }
  Res[edge] = C[node] - sum;
}
void Solve() {
  for (int i = 1; i <= N; i++) Use[i] = 0;
  SolveCase2(Cycle[0], 0, 0);
  int edge =
      Map[make_pair(min(Cycle[0], Cycle.back()), max(Cycle[0], Cycle.back()))];
  Res[edge] += Res[0] / 2;
  int sign = 1;
  for (int i = 0; i < Cycle.size() - 1; i++) {
    int e = Map[make_pair(min(Cycle[i], Cycle[i + 1]),
                          max(Cycle[i], Cycle[i + 1]))];
    Res[e] += sign * Res[0] / 2;
    sign *= -1;
  }
}
int main() {
  Read();
  DFS(1, 1);
  if (bipartite == 1) {
    SolveCase1(1, 0, 0);
    if (Res[0] != 0) {
      cout << "NO\n";
      return 0;
    }
  } else {
    findCycle(1, 0);
    Solve();
  }
  cout << "YES\n";
  for (int i = 1; i <= M; i++) cout << Res[i] << "\n";
  return 0;
}
