#include <bits/stdc++.h>
using namespace std;
template <typename T>
inline T read(register T& t) {
  register T f = 1;
  register char ch = getchar();
  t = 0;
  while (ch < '0' || ch > '9') {
    if (ch == '-') f = -f;
    ch = getchar();
  }
  while (ch >= '0' && ch <= '9') t = t * 10 + ch - '0', ch = getchar();
  t *= f;
  return t;
}
template <typename T, typename... Args>
inline void read(T& t, Args&... args) {
  read(t);
  read(args...);
}
const long long p = 998244353;
inline long long power(register long long x, register long long k = p - 2) {
  register long long re = 1;
  for (; k; k >>= 1, x = x * x % p)
    if (k & 1) re = re * x % p;
  return re;
}
int n, m;
int head[100005], ne[200005], to[200005], total = 1;
inline void add(int a, int b) {
  total++;
  to[total] = b;
  ne[total] = head[a];
  head[a] = total;
}
long long Ans[200005], c[200005];
bool vis[200005];
int fa[200005], fs[200005];
int deep[200005];
void dfs(int now) {
  vis[now] = 1;
  deep[now] = deep[fa[now]] + 1;
  for (int i = head[now]; i; i = ne[i])
    if (vis[to[i]] == 0) {
      fa[to[i]] = now;
      fs[to[i]] = i;
      dfs(to[i]);
    }
  if (fs[now]) {
    Ans[fs[now] >> 1] += c[now];
    c[fa[now]] -= c[now];
    c[now] = 0;
  }
}
void dfs2(int now) {
  if (c[1] == 0) return;
  for (int i = head[now]; i; i = ne[i])
    if (to[i] != fa[now]) {
      if (c[1] == 0) return;
      if (deep[to[i]] < deep[now]) continue;
      if (now != fa[to[i]] && (deep[to[i]] - deep[now]) % 2 == 0) {
        long long qwq = -c[1] / 2;
        if (deep[now] & 1) qwq = c[1] / 2;
        Ans[i >> 1] += qwq;
        int id;
        id = to[i];
        while (id != now) {
          qwq = -qwq;
          Ans[fs[id] >> 1] += qwq;
          id = fa[id];
        }
        qwq = c[1];
        if (deep[now] & 1) qwq = -c[1];
        id = now;
        while (id != 1) {
          Ans[fs[id] >> 1] += qwq;
          qwq = -qwq;
          id = fa[id];
        }
        c[1] = 0;
        return;
      }
      if (now == fa[to[i]]) dfs2(to[i]);
      if (c[1] == 0) return;
    }
}
int main() {
  read(n, m);
  for (int i = 1; i <= n; i++) read(c[i]);
  for (int i = 1, x, y; i <= m; i++) read(x, y), add(x, y), add(y, x);
  dfs(1);
  if (c[1] & 1) return printf("NO\n"), 0;
  dfs2(1);
  if (c[1]) return printf("NO\n"), 0;
  printf("YES\n");
  for (int i = 1; i <= m; i++) printf("%lld\n", Ans[i]);
  return 0;
}
