https://ac.nowcoder.com/acm/contest/317/D

题解：欧拉函数+快速幂

参考文章：

https://blog.csdn.net/weixin_43272781/article/details/85558253

https://blog.csdn.net/weixin_43272781/article/details/85058595

/*
*@Author:   STZG
*@Language: C++
*/
#include <bits/stdc++.h>
#include<iostream>
#include<algorithm>
#include<cstdlib>
#include<cstring>
#include<cstdio>
#include<string>
#include<vector>
#include<bitset>
#include<queue>
#include<deque>
#include<stack>
#include<cmath>
#include<list>
#include<map>
#include<set>
//#define DEBUG
#define RI register int
using namespace std;
typedef long long ll;
//typedef __int128 lll;
const int N=300000+10;
const int MOD=1e9+7;
const double PI = acos(-1.0);
const double EXP = 1E-8;
const int INF = 0x3f3f3f3f;
ll t,n,m,k,q;
int ans,cnt,temp,num;
ll a,b;
char str;
ll euler(ll n){ //返回euler(n)
     ll res=n,a=n;
     for(int i=2;i*i<=a;i++){
         if(a%i==0){
             res=res/i*(i-1);//先进行除法是为了防止中间数据的溢出
             while(a%i==0) a/=i;
         }
     }
     if(a>1) res=res/a*(a-1);
     return res;
}
ll PowerMod(ll a, ll b, ll c){
    ll ans = 1;
        a = a % c;
    while(b>0){
        if(b % 2 == 1)
            ans = (ans * a) % c;
        b >>= 1;
        a = (a * a) % c;
    }
    return ans;
}

int main()
{
#ifdef DEBUG
	freopen("input.in", "r", stdin);
	//freopen("output.out", "w", stdout);
#endif
    scanf("%lld%lld%lld%lld",&n,&k,&a,&b);
    int phi=euler(n);
    //cout<<phi<<endl;
    cout<<((a+b)*PowerMod(k,phi/2*n,MOD))%MOD<<endl;
    //cout << "Hello world!" << endl;
    return 0;
}