#include <cstdio>

 #include <stack>

 #include <cstring>

 using namespace std;

 int n, p, r1, cnt, idx, ans = , minn;

 int a[], next[], to[], head[], low[], dfn[], belong[], r[];

 bool ins[], vis[], mey[];

 stack <int> s;

 inline void add(int x, int y)

 {

     to[cnt] = y;

     next[cnt] = head[x];

     head[x] = cnt++;

 }

 void dfs(int u)

 {

     int i, v;

     vis[u] = ;

     mey[u] = ;

     for(i = head[u]; i != -; i = next[i])

     {

         v = to[i];

         if(!vis[v]) dfs(v);

     }

 }

 void tarjan(int u)

 {

     low[u] = dfn[u] = ++idx;

     s.push(u);

     ins[u] = ;

     int i, v;

     for(i = head[u]; i != -; i = next[i])

     {

         v = to[i];

         if(!dfn[v])

         {

             tarjan(v);

             low[u] = min(low[u], low[v]);

         }

         else if(ins[v]) low[u] = min(low[u], dfn[v]);

     }

     if(low[u] == dfn[u])

     {

         cnt++;

         do

         {

             v = s.top();

             s.pop();

             ins[v] = ;

             belong[v] = cnt;

         }while(u != v);

     }

 }

 int main()

 {

     int i, j, k, x, y, u, v;

     scanf("%d %d", &n, &p);

     for(i = ; i <= p; i++)

     {

         scanf("%d", &x);

         scanf("%d", &a[x]);

     }

     memset(head, -, sizeof(head));

     scanf("%d", &r1);

     for(i = ; i <= r1; i++)

     {

         scanf("%d %d", &x, &y);

         add(x, y);

     }

     for(i = ; i <= n; i++)

      if(!vis[i] && a[i])

       dfs(i);

     for(i = ; i <= n; i++)

      if(!mey[i])

       ans = min(ans, i);

     if(ans != )

     {

         printf("NO\n%d", ans);

         return ;

     }

     cnt = ;

     for(i = ; i <= n; i++)

      if(!dfn[i])

       tarjan(i);

     for(u = ; u <= n; u++)

      for(i = head[u]; i != -; i = next[i])

      {

          v = to[i];

          if(belong[u] != belong[v]) r[belong[v]]++;

      }

     ans = ;

     for(i = ; i <= cnt; i++)

      if(r[i] == )

      {

          minn = ;

          for(j = ; j <= n; j++)

           if(belong[j] == i && a[j])

            minn = min(minn, a[j]);

          ans += minn;

      }

     printf("YES\n%d", ans);

     return ;

 }