#include<bits/stdc++.h>
using namespace std;

int n, m, k;
vector<vector<int>> g;
vector<int> pos, dis, rem, ans;
void solve(){
    cin >> n >> m >> k;
    g.resize(n+1), pos.resize(k), dis.resize(k), rem.resize(n+1, -1);
    while(m--){
        int a, b; cin >> a >> b;
        g[a].push_back(b);
        g[b].push_back(a);
    }
    queue<int> q;
    for(int i=0; i<k; ++i)
        cin >> pos[i] >> dis[i], 
        rem[pos[i]] = dis[i],
        q.push(pos[i]);
    
    while(!q.empty()){
        auto cur = q.front(); q.pop();
        if(rem[cur] == 0) continue;
        for(auto v: g[cur]){
            if(rem[v] < rem[cur] - 1)
                rem[v] = rem[cur] - 1,
                q.push(v);
        }
    }
    for(int i=1; i<=n; ++i)
        if(rem[i] != -1)
            ans.push_back(i);
    
    cout << (int)(ans.size()) << '\n';
    for(auto x: ans) cout << x << ' ';
}
signed main(){
    ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
    solve();
}