#include<iostream>
using namespace std;
long long n,m,minb,a[200005],b[200005];
int main(){
	cin>>n>>m;
	minb=m;
	for(int i=1;i<=n;i++)cin>>a[i];
	for(int i=1;i<=n;i++){
		cin>>b[i];
		minb=min(minb,b[i]+a[i]);
	}
	long long l=0,r=minb,mid;
	while(l<=r){
		mid=(l+r)/2;
		long long ans=0;
		for(int i=1;i<=n;i++){
			if(a[i]<mid)ans+=mid-a[i];
		}
		if(ans>=m)r=mid-1;
		else l=mid+1;
	}
	cout<<mid;
	return 0;
}

一直 WA on #10