#include<bits/stdc++.h>
using namespace std;
#define IOS ios::sync_with_stdio(0),cin.tie(0),cout.tie(0);
#define int long long
#define inf 0x3f3f3f3f
#define mod1 1000000007
#define mod2 998244353
#define f first
#define s second
#define pb push_back
#define eb emplace_back
#define fo(i,a,b) for(int i=a;i<=b;i++)
#define rep(i,a,b) for(int i=a;i>=b;i--)
#define m1(a,b) memset(a,b,sizeof a)
#define m2(a,b) memcpy(a,b,sizeof b)
using ld = long double;
using str = string;
using pi = pair<int,int>;
using pd = pair<ld,ld>;
using vi = vector<int>;
using vb = vector<bool>;
using vd = vector<ld>; 
using vs = vector<str>;
using vpi = vector<pi>;
using vpd = vector<pd>;
const ld PI = acos((ld)-1);
const int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
template<class T> using pqg = priority_queue<T,vector<T>,greater<T>>;
template<typename T, typename U> void umin(T& a, U b){if (a > b) a = b;}
template<typename T, typename U> void umax(T& a, U b){if (a < b) a = b;}
namespace IO{
    inline int read()
    {
        int X=0; bool flag=1; char ch=getchar();
        while(ch<'0'||ch>'9') {if(ch=='-') flag=0; ch=getchar();}
        while(ch>='0'&&ch<='9') {X=(X<<1)+(X<<3)+ch-'0'; ch=getchar();}
        if(flag) return X;
        return ~(X-1);
    }
    inline void write(int X)
    {
        if(X<0) {X=~(X-1); putchar('-');}
        if(X>9) write(X/10);
        putchar(X%10+'0');
    }
}
namespace math{
    int qmi(int a,int k,int p)
    {
        int res=1%p;
        while(k)
        {
            if(k&1) res=res*a%p;
            a=a*a%p;
            k>>=1;
        }
        return res;
    }
    bool is_prime(int x)  
    {
        if (x < 2) return false;
        for (int i = 2; i <= x / i; i ++ )
            if (x % i == 0)
                return false;
        return true;
    }
    int gcd(int a,int b)
    {
        return b?gcd(b,a%b):a;
    }
    int exgcd(int a,int b,int &x,int &y) 
    {
        if(!b)
        {
            x=1;y=0;
            return a;
        }
        int d=exgcd(b,a%b,y,x);
        y-=(a/b)*x;
        return d;
    }
    vector<int> add(vector<int> &A, vector<int> &B)  // C = A + B, A >= 0, B >= 0
    {
        if (A.size() < B.size()) return add(B, A);
        vector<int> C;
        int t = 0;
        for (int i = 0; i < A.size(); i ++ )
        {
            t += A[i];
            if (i < B.size()) t += B[i];
            C.push_back(t % 10);
            t /= 10;
        }
        if (t) C.push_back(t);
        return C;
    }
    vector<int> sub(vector<int> &A, vector<int> &B)  // C = A - B, 满足A >= B, A >= 0, B >= 0
    {
        vector<int> C;
        for (int i = 0, t = 0; i < A.size(); i ++ )
        {
            t = A[i] - t;
            if (i < B.size()) t -= B[i];
            C.push_back((t + 10) % 10);
            if (t < 0) t = 1;
            else t = 0;
        }

        while (C.size() > 1 && C.back() == 0) C.pop_back();
        return C;
    }
    vector<int> mul(vector<int> &A, int b)  // C = A * b, A >= 0, b >= 0
    {
        vector<int> C;

        int t = 0;
        for (int i = 0; i < A.size() || t; i ++ )
        {
            if (i < A.size()) t += A[i] * b;
            C.push_back(t % 10);
            t /= 10;
        }

        while (C.size() > 1 && C.back() == 0) C.pop_back();

        return C;
    }
    vector<int> div(vector<int> &A, int b, int &r)  // A / b = C ... r, A >= 0, b > 0
    {
        vector<int> C;
        r = 0;
        for (int i = A.size() - 1; i >= 0; i -- )
        {
            r = r * 10 + A[i];
            C.push_back(r / b);
            r %= b;
        }
        reverse(C.begin(), C.end());
        while (C.size() > 1 && C.back() == 0) C.pop_back();
        return C;
    }
}
namespace tu{
    int h[100010],w[100010],e[100010],ne[100010],idx;
    void add(int a,int b)
    {
        e[idx]=b,ne[idx]=h[a],h[a]=idx++;
    }
    void add(int a,int b,int c)
    {
        e[idx]=b,w[idx]=c,ne[idx]=h[a],h[a]=idx++;
    }
}
using namespace IO;
using namespace math;
using namespace tu;
signed main(){
    return 0;
}

159行。