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 + 50;
struct Edg {
  int d, ind;
};
vector<Edg> g[N];
int n, m, col[N], vis[N], pre[N], pre_ind[N];
int cir_s, cir_t, cir_edg, dfn[N];
bool act[N], find_odd_circle;
long long ans[N], c[N];
void dfs(int v) {
  vis[v] = true;
  for (auto t : g[v]) {
    int d = t.d, ind = t.ind;
    if (!vis[d]) {
      col[d] = col[v] ^ 1;
      pre[d] = v;
      pre_ind[d] = ind;
      dfn[d] = dfn[v] + 1;
      act[ind] = true;
      dfs(d);
    } else if (dfn[d] < dfn[v]) {
      if (col[v] == col[d]) {
        find_odd_circle = true;
        cir_s = v, cir_t = d;
        cir_edg = ind;
      }
    }
  }
}
void solve_tree(int v) {
  vis[v] = 1;
  ;
  for (auto t : g[v]) {
    int d = t.d, ind = t.ind;
    if (vis[d] || (!act[ind])) continue;
    solve_tree(d);
    ;
    ans[ind] = c[d];
    c[d] = 0;
    c[v] -= ans[ind];
  }
}
int main(int argc, char *argv[]) {
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= (n); ++i) {
    scanf("%lld", c + i);
  }
  for (int i = 1; i <= (m); ++i) {
    int a, b;
    scanf("%d%d", &a, &b);
    g[a].push_back(Edg{b, i});
    g[b].push_back(Edg{a, i});
  }
  dfs(1);
  if (!find_odd_circle) {
    memset(vis, 0, sizeof(vis));
    solve_tree(1);
    if (c[1] == 0) {
      printf("YES\n");
      for (int i = 1; i <= (m); ++i) printf("%lld\n", ans[i]);
      return 0;
    } else {
      printf("NO\n");
    }
  } else {
    memset(vis, 0, sizeof(vis));
    solve_tree(cir_s);
    ;
    for (int i = 1; i <= (n); ++i)
      ;
    for (int i = 1; i <= (m); ++i)
      ;
    long long w = c[cir_s] / 2, f = 1;
    for (int v = cir_s; v != cir_t; v = pre[v]) {
      ans[pre_ind[v]] += f * w;
      f = -f;
    }
    ans[cir_edg] += f * w;
    for (int i = 1; i <= (m); ++i) printf("%lld\n", ans[i]);
  }
}
