#include <bits/stdc++.h>
const long long N = 2e5 + 52;
struct edge {
  long long to, next;
} e[N << 1];
long long head[N], cnt = 1;
void addedge(long long x, long long y) {
  e[++cnt] = (edge){y, head[x]}, head[x] = cnt;
  e[++cnt] = (edge){x, head[y]}, head[y] = cnt;
}
struct dsu {
  long long p[N];
  long long f(long long x) { return p[x] ? p[x] = f(p[x]) : x; }
  void m(long long x, long long y) {
    if ((x = f(x)) != (y = f(y))) p[x] = y;
  }
} _;
long long a[N], v[N], c[N], d[N], P[N];
void dfs(long long x, long long p) {
  for (long long i = head[x], nx; i; i = e[i].next)
    if ((nx = e[i].to) != p)
      c[nx] = !c[x], d[nx] = d[x] + 1, P[nx] = x, dfs(nx, x), v[x] -= v[nx],
      a[i / 2] += v[nx], v[nx] = 0;
}
long long n, m, x[N], y[N], a0[N], v0[N];
bool f[N];
signed main() {
  scanf("%I64d%I64d", &n, &m);
  for (long long i = 1; i <= n; i++) scanf("%I64d", v + i);
  for (long long i = 1; i <= m; i++) {
    scanf("%I64d%I64d", x + i, y + i);
    if (_.f(x[i]) != _.f(y[i]))
      f[i] = true, addedge(x[i], y[i]), _.m(x[i], y[i]);
    else
      cnt += 2;
  }
  c[1] = 1, dfs(1, 0);
  if (v[1] % 2) return puts("NO"), 0;
  if (!v[1]) {
    puts("YES");
    for (long long i = 1; i <= m; i++) printf("%I64d\n", a[i]);
    return 0;
  }
  memcpy(a0, a, sizeof a), memcpy(v0, v, sizeof v);
  for (long long i = 1, s, t; i <= m; i++) {
    if (f[i] || c[s = x[i]] != c[t = y[i]]) continue;
    long long val = v[1] / 2;
    v[s] -= val, v[t] -= val, a[i] += val, dfs(1, 0);
    if (v[1]) {
      memcpy(a, a0, sizeof a), memcpy(v, v0, sizeof v);
      v[s] += val, v[t] += val, a[i] -= val, dfs(1, 0);
    }
    puts("YES");
    for (long long j = 1; j <= m; j++) printf("%I64d\n", a[j]);
    return 0;
  }
  puts("NO");
}
