#include <bits/stdc++.h>
using namespace std;
int n, m, f[100010], tot = 1, head[100010], col[100010], spe, root;
int bk[100010], v[100010];
long long a[100010], w[100010];
bool flag[100010];
inline int find(int x) {
  if (x == f[x]) return x;
  return f[x] = find(f[x]);
}
struct rd {
  int now, next, to;
} road[200010];
inline void addedge(int x, int y) {
  road[++tot].next = head[x];
  road[tot].to = y;
  road[tot].now = x;
  head[x] = tot;
}
inline void dfs(int x) {
  for (int now = head[x]; now; now = road[now].next)
    if (col[road[now].to] != 2) {
      if (col[road[now].to] == col[x] && spe == 0)
        spe = x, root = x, bk[road[now].to] = now;
    } else {
      col[road[now].to] = col[x] ^ 1;
      flag[now >> 1] = 1;
      if (spe == 0) bk[road[now].to] = now;
      dfs(road[now].to);
    }
}
inline void dfs(int x, int fa) {
  for (int now = head[x]; now; now = road[now].next) {
    if (road[now].to != fa && flag[now >> 1] == 1) {
      dfs(road[now].to, x);
      a[now >> 1] = v[road[now].to] - w[road[now].to];
      w[x] += a[now >> 1];
    }
  }
}
int main() {
  cin >> n >> m;
  for (int i = 1; i <= n; i++) f[i] = i;
  for (int i = 1; i <= n; i++) scanf("%d", &v[i]);
  for (int i = 1, x, y; i <= m; i++)
    scanf("%d%d", &x, &y), addedge(x, y), addedge(y, x);
  for (int i = 1; i <= n; i++) col[i] = 2;
  col[1] = 0;
  dfs(1);
  if (spe == 0) {
    long long V = 0;
    for (int i = 1; i <= n; i++)
      if (col[i] == 0)
        V += v[i];
      else
        V -= v[i];
    if (V != 0)
      printf("NO\n");
    else {
      printf("YES\n");
      dfs(1, 0);
      for (int i = 1; i <= m; i++) printf("%I64d\n", a[i]);
    }
    return 0;
  } else {
    printf("YES\n");
    dfs(root, 0);
    a[bk[root] >> 1] += (v[root] - w[root]) / 2;
    for (int i = road[bk[root]].now, j = -1; i != root;
         i = road[bk[i]].now, j *= -1)
      a[bk[i] >> 1] += j * (v[root] - w[root]) / 2;
    for (int i = 1; i <= m; i++) printf("%I64d\n", a[i]);
  }
  return 0;
}
