#include <cmath>
#include <iostream>
#include <vector>
#include <algorithm>
#include <string>
#include <set>
#include <map>
#include <list>
#include <time.h>
#include <math.h>
#include <random>
#include <deque>
#include <queue>
#include <cassert>
#include <unordered_map>
#include <iomanip>
#include <bitset>

using namespace std;

typedef long long ll;

mt19937 rnd(228);

const int N = 1e5 + 7;

vector <pair <int, int> > g[N];

ll c[N];
ll cur[N];
ll ans[N];
bool u[N];
int col[N];
int par[N];
int d[N];
int par_ind[N];

int s = -1, t = -1;
int edge_ind = -1;

void dfs(int v)
{
    u[v] = true;
    for (auto x : g[v])
    {
        int to = x.first, ind = x.second;
        if (!u[to])
        {
            d[to] = d[v] + 1;
            col[to] = (col[v] ^ 1);
            par[to] = v;
            par_ind[to] = ind;
            dfs(to);
            ans[ind] = cur[to];
            cur[v] -= cur[to];
        }
        else if (d[to] < d[v])
        {
            if (col[to] == col[v])
            {
                s = v, t = to;
                edge_ind = ind;
            }
        }
    }
}

void solve_tree(int v)
{
    u[v] = true;
    for (auto x : g[v])
    {
        int to = x.first, ind = x.second;
        if (ind != edge_ind && !u[to])
        {
            solve_tree(to);
            ans[ind] = c[to];
            c[v] -= c[to];
        }
    }
}


int main()
{
#ifdef ONPC
    freopen("a.in", "r", stdin);
#endif
    int n, m;
    scanf("%d%d", &n, &m);
    for (int i = 0; i < n; i++)
    {
        scanf("%lld", &c[i]);
        cur[i] = c[i];
    }
    for (int i = 0; i < m; i++)
    {
        int a, b;
        scanf("%d%d", &a, &b);
        a--, b--;
        g[a].push_back({b, i});
        g[b].push_back({a, i});
    }
    dfs(0);
    if (cur[0] == 0)
    {
        puts("YES");
        for (int i = 0; i < m; i++)
        {
            printf("%lld\n", ans[i]);
        }
        return 0;
    }
    if (edge_ind != -1)
    {
        for (int i = 0; i < m; i++)
        {
            ans[i] = 0;
        }
        for (int i = 0; i < n; i++)
        {
            u[i] = 0;
        }
        solve_tree(s);
        ll get = c[s] / 2;
        int cur = s;
        int sign = 1;
        while (cur != t)
        {
            ans[par_ind[cur]] += sign * get;
            sign *= -1;
            cur = par[cur];
        }
        ans[edge_ind] += sign * get;
        puts("YES");
        for (int i = 0; i < m; i++)
        {
            printf("%lld\n", ans[i]);
        }
    }
    else
    {
        puts("NO");
        return 0;
    }
}