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;
struct edge {
  int from, to;
  long long w;
};
const int MAXN = 1e5 + 5;
int n, m;
vector<int> g[MAXN];
vector<int> cycle;
edge e[MAXN];
bool used[MAXN];
long long c[MAXN];
int color[MAXN], edge_p[MAXN], node_p[MAXN];
int start;
void clear_used() {
  for (int i = 0; i < n; ++i) used[i] = false;
}
int get_link(int v, int id) {
  return (v == e[id].from ? e[id].to : e[id].from);
}
bool dfs_duo(int v, int parent_id) {
  used[v] = true;
  for (int id : g[v]) {
    int u = get_link(v, id);
    if (!used[u]) {
      color[u] = (1 ^ color[v]);
      edge_p[id] = parent_id;
      node_p[u] = v;
      if (!dfs_duo(u, id)) return false;
    } else if (color[u] == color[v]) {
      edge_p[id] = parent_id;
      start = u;
      for (int node = v; node != start; node = node_p[node], id = edge_p[id])
        cycle.push_back(id);
      cycle.push_back(id);
      return false;
    }
  }
  return true;
}
void dfs_solve(int v, int parent_id) {
  used[v] = true;
  for (int id : g[v]) {
    int u = get_link(v, id);
    if (!used[u]) {
      dfs_solve(u, id);
      c[v] -= e[id].w;
    }
  }
  if (parent_id != -1) e[parent_id].w = c[v];
}
int main() {
  scanf("%d%d", &n, &m);
  for (int i = 0; i < n; ++i) scanf("%d", &c[i]);
  for (int i = 0; i < m; ++i) {
    scanf("%d%d", &e[i].from, &e[i].to);
    e[i].w = 0;
    --e[i].from;
    --e[i].to;
    g[e[i].from].push_back(i);
    g[e[i].to].push_back(i);
  }
  color[0] = 0;
  clear_used();
  if (dfs_duo(0, -1)) {
    long long sum[2];
    sum[0] = 0;
    sum[1] = 0;
    for (int i = 0; i < n; ++i) sum[color[i]] += c[i];
    if (sum[0] != sum[1]) {
      printf("NO");
      return 0;
    }
    clear_used();
    dfs_solve(0, -1);
  } else {
    clear_used();
    dfs_solve(start, -1);
    int add = c[start] / 2;
    for (int i = 0; i < (int)cycle.size(); ++i)
      e[cycle[i]].w += (i & 1 ? -add : add);
  }
  printf("YES\n");
  for (int i = 0; i < m; ++i) printf("%d\n", e[i].w);
}
