#include <bits/stdc++.h>
using namespace std;
typedef struct node {
  int first, second, third;
  node() {}
  node(int a, int b, int c) { first = a, second = b, third = c; }
} triple;
vector<triple> G;
vector<int> hd, mark, path, c, _path;
vector<long long> wh;
void add(int u, int v, int w) {
  G.push_back(triple(v, hd[u], w));
  hd[u] = G.size() - 1;
}
int trav(int x, int t) {
  int i, j, tmp, k;
  path.push_back(x);
  mark[x] = t;
  for (i = hd[x]; ~i; i = G[i].second) {
    j = G[i].first;
    if (mark[j]) {
      if (mark[j] == mark[x]) {
        for (k = path.size() - 1; path[k] != j; k--)
          ;
        _path.clear();
        for (; k != path.size(); k++) _path.push_back(path[k]);
        return j;
      }
    } else {
      tmp = trav(j, 3 - t);
      if (~tmp) return tmp;
    }
  }
  path.pop_back();
  return -1;
}
void wt(int x, int e) {
  long long w;
  int i, j, k;
  mark[x] = 1;
  w = c[x];
  for (i = hd[x]; ~i; i = G[i].second) {
    j = G[i].first;
    k = G[i].third;
    if (!mark[j]) {
      wt(j, k);
      w -= wh[k];
    }
  }
  if (~e) wh[e] = w;
}
void cyc(int x, int t, long long d) {
  int i, j;
  for (i = hd[x]; ~i; i = G[i].second) {
    j = G[i].first;
    if (j != (t == _path.size() ? _path[0] : _path[t])) continue;
    wh[G[i].third] += d;
    if (t != _path.size()) cyc(j, t + 1, -d);
    return;
  }
}
int main() {
  int n, m, i, u, v, vtx;
  long long delt;
  scanf("%d%d", &n, &m);
  c.clear();
  for (i = 0; i < n; i++) {
    scanf("%d", &v);
    c.push_back(v);
  }
  hd.clear();
  hd.resize(n, -1);
  G.clear();
  for (i = 0; i < m; i++) {
    scanf("%d%d", &u, &v);
    u--, v--;
    add(u, v, i), add(v, u, i);
  }
  wh.clear();
  wh.resize(m, 0LL);
  mark.clear();
  mark.resize(n, 0);
  path.clear();
  vtx = trav(0, 1);
  mark.clear();
  mark.resize(n, 0);
  wt(~vtx ? vtx : 0, -1);
  delt = c[~vtx ? vtx : 0];
  for (i = hd[~vtx ? vtx : 0]; ~i; i = G[i].second) {
    delt -= wh[G[i].third];
  }
  if (vtx == -1 && delt != 0) {
    printf("NO\n");
    return 0;
  }
  if (~vtx) {
    cyc(vtx, 1, delt / 2);
  }
  printf("YES\n");
  for (i = 0; i < m; i++) {
    printf("%lld\n", wh[i]);
  }
  return 0;
}
