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#include<iostream>
#include<cstdio>
#include<queue>
using namespace std;
const int MAXN=3005,MAXM=1e4+5,inf=1e9;
int n,p,r,ans,cnt,cnt2,head2[MAXN],head[MAXN],dfn[MAXN],vis[MAXN],low[MAXN],stack[MAXN],top,num,color,col[MAXN],val[MAXN],minn[MAXN],deg[MAXN];
bool control[MAXN];
struct edge{
	int nx,to,from;
}edge[MAXM],e[MAXM];
inline int read()
{
	int x=0,f=1;
	char ch=getchar();
	while(!isdigit(ch))
	{
		if(ch=='-') f=-1;
		ch=getchar(); 
	}
	while(isdigit(ch))
	{
		x=x*10+ch-'0';
		ch=getchar();
	}
	return x*f;
}
void add_edge(int u,int v)
{
	edge[++cnt].from=u;
	edge[cnt].to=v;
	edge[cnt].nx=head[u];
	head[u]=cnt;
}
void tarjan(int u)
{
	dfn[u]=low[u]=++num;
	vis[u]=1;
	stack[++top]=u;
	for(int i=head[u];i;i=edge[i].nx)
	{
		int v=edge[i].to;
		if(!dfn[v])
		{
			tarjan(v);
			low[u]=min(low[u],low[v]);
		}
		else if(vis[v])
		{
			low[u]=min(low[u],dfn[v]);
		}
	}
	if(dfn[u]==low[u])
	{
		color++;
		while(stack[top+1]!=u)
		{
			col[stack[top]]=color;
			vis[stack[top]]=0;
			minn[color]=min(minn[color],val[stack[top--]]);
		}
	}
}
int main()
{
	n=read(),p=read();
	for(int i=1;i<=n;i++) val[i]=inf,minn[i]=inf;
	for(int i=1;i<=p;i++)
	{
		int a=read(),b=read();
		val[a]=b;
	}
	r=read();
	for(int i=1;i<=r;i++)
	{
		int u=read(),v=read();
		add_edge(u,v);
	}
	for(int i=1;i<=n;i++)
		if(!dfn[i] && val[i]!=inf) tarjan(i);
	for(int i=1;i<=n;i++)
		if(!dfn[i])
		{
			printf("NO\n%d",i);
			return 0;
		}
	for(int i=1;i<=n;i++)
		for(int j=head[i];j;j=edge[j].nx)
			if(col[i]!=col[edge[i].to])
				deg[col[edge[j].to]]++;
	printf("YES\n");
	for(int i=1;i<=color;i++)
	{
		if(!deg[i])
		{
			ans+=minn[i];
		}
	}
	printf("%d",ans);
	return 0;
}