zm吃包子

#include<bits/stdc++.h>
using namespace std;
const int N=1e6+5;
int n,q,size,ans[N],ge,cnt1,cnt2,sh[N],dq[N],dui[N],cj,cc[N];
struct ztef
{
    int x1,x2,y1,y2,k,id;
}a[N<<1],huan2[N];
struct cha
{
    int qi,ho;
}b[N],huan[N];
struct line
{
    int he,ze1,ze2,pu,du;
}li[N<<1];
string s,ss;
struct pigu
{
    int er[N][27],dfn[N],cnt,siz[N];
    inline int insert(string x)
    {
        int len=x.size(),now=0;
        for(int i=0;i<len;i++)
        {
            if(!er[now][x[i]-‘a‘]) er[now][x[i]-‘a‘]=++cnt;
            now=er[now][x[i]-‘a‘];
        }
        return now;
    }
    inline void dfs(int now)
    {
        dfn[now]=++size;siz[now]=1;
        for(int i=0;i<=25;i++)
        {
            if(!er[now][i]) continue;
            dfs(er[now][i]);
            siz[now]+=siz[er[now][i]];
        }
    }
    inline int cha(string x)
    {
        int now=0,len=x.size();
        for(int i=0;i<len;i++)
        {
            if(!er[now][x[i]-‘a‘]) return 0;
             now=er[now][x[i]-‘a‘];
        }
        return now;
    }
}zh,fa;
inline int read()
{
    char c=getchar();
    int x=0,f=1;
    while(!isdigit(c)) {if(c==‘-‘) f=-1;c=getchar();}
    while(isdigit(c)) {x=(x<<3)+(x<<1)+c-‘0‘;c=getchar();}
    return x*f;
}
inline int lowbit(int x)
{
    return x&(-x);
}
inline void update(int now,int v)
{
    while(now<=cj)
    {
        sh[now]+=v;
        now+=lowbit(now);
    }
}
inline int query(int now)
{
    int daan=0;
    if(now<=0) return 0;
    while(now)
    {
        daan+=sh[now];
        now-=lowbit(now);
    }
    return daan;
}
inline bool cmp2(line x,line y)
{
    return x.he<y.he;
}
inline bool cmp1(cha x,cha y)
{
    return x.qi<y.qi;
}
inline void solve(int l,int r,int L,int R)
{
    if(L>R) return;
    if(l==r)
    {
        if(r==n+1) for(int i=L;i<=R;i++) ans[dui[i]]=-1;
        else for(int i=L;i<=R;i++) ans[dui[i]]=l;
        return;
    }
    int cn3=1,mid=(l+r)>>1,cn1=0,cn2=0;
    for(int i=l;i<=mid;i++)
        huan[++cn1]=b[i];
    sort(huan+1,huan+cn1+1,cmp1);
    for(int i=L;i<=R;i++)
    {
        if(ans[dui[i]]==-1) continue;
        li[++cn2]=(line){a[dui[i]].x1-1,a[dui[i]].y1,a[dui[i]].y2,-1,i};
        li[++cn2]=(line){a[dui[i]].x2,a[dui[i]].y1,a[dui[i]].y2,1,i};
    }
    sort(li+1,li+cn2+1,cmp2);
    for(int i=1;i<=cn2;i++)
    {
        while(cn3<=cn1&&huan[cn3].qi<=li[i].he)
        {
            update(huan[cn3].ho,1);
            cn3++;
        }
        dq[li[i].du]+=(query(li[i].ze2)-query(li[i].ze1-1))*li[i].pu;
    }
    for(int i=1;i<cn3;i++)
        update(huan[i].ho,-1);
    int hu1=L,hu2=R;
    for(int i=L;i<=R;i++)
    {
        if(dq[i]>=a[dui[i]].k)
            cc[hu1++]=dui[i];
        else
        {
            cc[hu2--]=dui[i];
            a[dui[i]].k-=dq[i];
        }
        dq[i]=0;
    }
    for(int i=L;i<=R;i++) dui[i]=cc[i];
    solve(l,mid,L,hu1-1);
    solve(mid+1,r,hu2+1,R);
}
int main()
{
    n=read();q=read();
    for(int i=1;i<=n;i++)
    {
        cin>>s;
        b[i].qi=zh.insert(s);
        reverse(s.begin(),s.end());
        b[i].ho=fa.insert(s);
    }
    zh.dfs(0);size=0;fa.dfs(0);
    for(int i=1;i<=n;i++)
    {
        b[i].qi=zh.dfn[b[i].qi];
        b[i].ho=fa.dfn[b[i].ho];
    }
    cj=fa.cnt+1;
    for(int i=1,x,y,z;i<=q;i++)
    {
        cin>>s>>ss>>z;
        dui[i]=i;
        reverse(ss.begin(),ss.end());
        x=zh.cha(s);
        y=fa.cha(ss);a[i].k=z;
        if(x==0||y==0) {ans[i]=-1;continue;}
        a[i].id=i;
        a[i].x1=zh.dfn[x];a[i].x2=zh.dfn[x]+zh.siz[x]-1;
        a[i].y1=fa.dfn[y];a[i].y2=fa.dfn[y]+fa.siz[y]-1;
    } 
    solve(1,n+1,1,q);
    for(int i=1;i<=q;i++) cout<<ans[i]<<"\n";
    return 0;
}