#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cstring>
#include<cmath>
#include<queue>
#define ll long long
using namespace std;
const int MN=1e5+5;
ll n,m,ans,cnt,a[MN],b[MN];
struct node{
    ll val,id,op;
    friend bool operator < (node a, node b){return a.val<b.val;}
};
priority_queue<node>q;
void write(ll n){if(n<0){putchar('-');write(-n);return;}if(n>9)write(n/10);putchar(n%10+'0');}
ll read(){ll x=0,f=1;char ch=getchar();while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}while(ch>='0'&&ch<='9'){x=(x<<1)+(x<<3)+(ch^48);ch=getchar();}return x*f;}
int main(){
    n=read();m=read();
    for(int i=1; i<=n; i++){a[i]=read();q.push({a[i],i,1});}
    for(int i=1; i<=n; i++) b[i]=read();
    while(m--){
        cnt+=q.top().val;ans^=cnt;ll id=q.top().id,op=q.top().op;q.pop();
        if(op==1) q.push({b[id],id,2});
        if(op==2) q.push({a[id],id,3});
    }
    write(ans);putchar('\n');
    return 0;
}