#include<bits/stdc++.h>
using namespace std;
const int mod=998244353;
namespace wxh666{
    #define getchar getchar_unlocked
    #define putchar putchar_unlocked
    #define sqrt(a) __builtin_sqrt(a)
    #define f(a,b,c) for(int a=b;a<=c;a++)
    #define ff(a,b,c) for(int a=b;a>=c;a--)
    #define g(n) f(i,1,n)
    #define df(n,m) g(n) f(j,1,m)
    #define max max_by_wxh
    template<typename T>
    inline T max_by_wxh(T x,T y) {return ((x)>(y)?(x):y);}
    template<typename T,typename ...Args>
    inline T max_by_wxh(T x,Args ...xs) {return max_by_wxh(x,max_by_wxh(xs...));}
    #define min min_by_wxh
    template<typename T>
    inline T min_by_wxh(T x,T y) {return ((x)<(y)?(x):y);}
    template<typename T,typename ...Args>
    inline T min_by_wxh(T x,Args ...xs) {return min_by_wxh(x,min_by_wxh(xs...));}
    template<typename T>
    inline void read(T &ans)
    {
        char ch=getchar();int f=1;ans=0;
        for(;!isdigit(ch);ch=getchar()) ch=='-'?f=-1:f=1;
        for(;isdigit(ch);ch=getchar()) ans=(ans<<3)+(ans<<1)+(ch&15);
        ans*=f;
        return;
    }
    template<typename T,typename ...Args>
    inline void read(T &tmp,Args &...tmps){read(tmp);read(tmps...);}
    inline int read()
    {
        char ch=getchar();int f=1,ans=0;
        for(;!isdigit(ch);ch=getchar()) ch=='-'?f=-1:f=1;
        for(;isdigit(ch);ch=getchar()) ans=(ans<<3)+(ans<<1)+(ch&15);
        return f*ans;
    }
    #define in read()
    template<typename T>
    inline void pu(T x)
    {
        ios::sync_with_stdio(false);
        cout<<x;
        ios::sync_with_stdio(true);
        return;
    }
    template<typename T>
    inline void pk(T x)
    {
        ios::sync_with_stdio(false);
        cout<<x<<" ";
        ios::sync_with_stdio(true);
        return;
    }
    inline void pk(char x)
    {
        ios::sync_with_stdio(false);
        cout<<x;
        if(x!='\n') cout<<' ';
        ios::sync_with_stdio(true);
        return;
    }
    template<typename T,typename ...Args>
    inline void pu(T x,Args ...xs){pu(x);pu(xs...);}
    template<typename T,typename ...Args>
    inline void ppu(T x,Args ...xs){pu(x,xs...,'\n');}
    template<typename T,typename ...Args>
    inline void pk(T x,Args ...xs){pk(x);pk(xs...);}
    template<typename T,typename ...Args>
    inline void ppk(T x,Args ...xs){pk(x,xs...,'\n');}
    #define cs(dt,n,m) \
    for(int i=1;i<=n;i++)\
    {\
        for(int j=1;j<=m;j++)\
            printf("%d ",dt[i][j]);\
        cout<<endl;\
    }
};using namespace wxh666;
namespace FILES{
    // #define FILE
    #ifdef FILE
    string file="";
    struct File{File(){freopen((file+".in").c_str(),"r",stdin);freopen((file+".out").c_str(),"w",stdout);}}files;
    #endif
};using namespace FILES;
namespace lsq {
    typedef int lsqxx;
    struct lq {
        struct lqbz {
            lsqxx v,w,nxt;
        } e[400005];
        lsqxx h[200005],cnt;
        inline void add(lsqxx u,lsqxx v,lsqxx w=1) {
            e[++cnt].v=v;
            e[cnt].w=w;
            e[cnt].nxt=h[u];
            h[u]=cnt;
        }
        void erase() {cnt=0;memset(h,0,sizeof(h));return;}
    #define F(z,u) for(int j=z.h[u],v=z.e[j].v,w=z.e[j].w;j;j=z.e[j].nxt,v=z.e[j].v,w=z.e[j].w)
    }q;
};using namespace lsq;
vector<pair<int,int> >qu[200005];
int n,m,p;
int sz[200005],d[200005];
int f[200005],dp[200005];
int ans;
void getsz(int u=1,int fa=1)
{
    sz[u]=1;d[u]=d[fa]+1;
    F(q,u)
    {
        if(v==fa) continue;
        getsz(v,u);
        sz[u]+=sz[v];
        f[u]=(f[u]+f[v]+sz[v]*w)%mod;
        ans=(ans+w*sz[v]*(n-sz[v]))%mod;
    }
}
int anss[200005];
void dfs(int u=1,int fa=1)
{
    for(auto i:qu[u]) anss[i.second]=(dp[u]+i.first*n+ans)%mod;
    F(q,u)
    {
        if(v==fa) continue;
        dp[v]=((dp[u]-w*sz[v]+w*(n-sz[v]))%mod+mod)%mod;
        dfs(v,u);
    }
}
int main()
{
    cin>>n>>p;
    g(n-1)
    {
        int x,y,z;
        read(x,y,z);
        q.add(x,y,z);
        q.add(y,x,z);
        m+=z;
    }
    g(p)
    {
        int k,w;
        read(k,w);
        qu[k].push_back(make_pair(w,i));
    }
    getsz();
    dp[1]=f[1];
    dfs();
    g(p) printf("%lld\n",2*anss[i]);
    return 0;
}

样例过了，但0pts.