#include <iostream>
#include<cstdio>
#include<vector>
#include<cstring>
#include<queue>
#include<algorithm>
using namespace std;
typedef pair<int,int>PII;
const int INF=100000;
const int maxn=1000+5;
struct Edge{
int to,weight;
Edge(int to,int weight):to(to),weight(weight) {}
};
int v,e;
int d[maxn];
vector<Edge>G[maxn];
bool done[maxn];
void dijkstra(int start)
{
memset(done,false,sizeof(done));
for(int i=1;i<=v;i++)
d[i]=(i==start?0:INF);
priority_queue<PII,vector<PII>,greater<PII> >pq;
pq.push(PII(d[start],start));
while(!pq.empty())
{
PII k=pq.top();
pq.pop();
int distance=k.first;
int vist=k.second;
if(done[vist]) continue;
done[vist]=true;
for(int i=0;i<G[vist].size();i++)
{
int k=G[vist][i].to;
if(d[k]>d[vist]+G[vist][i].weight)
{
d[k]=d[vist]+G[vist][i].weight;
pq.push(PII(d[k],k));
}
}
}
}
int main()
{
scanf(“%d%d”,&v,&e);
for(int i=0;i<e;i++)
{
int v1,v2,dist;
scanf(“%d%d%d”,&v1,&v2,&dist);
/*避免重边*/
bool flag=false;
for(int i=0;i<G[v1].size();i++)
{
if(G[v1][i].to==v2) {
flag=true;
if(dist<G[v1][i].weight) G[v1][i].weight=dist;
break;
}
}
if(!flag) G[v1].push_back(Edge(v2,dist));
}
int start,end;
while(scanf(“%d%d”,&start,&end)==2)
{
dijkstra(start);
if(d[end]>=INF) printf(“No\n”);
else {
printf(“Yes\n”);
printf(“%d\n”,d[end]);
}
}
return 0;
}