AC

#include<iostream>
#include<algorithm>
using namespace std;
const int N=1e6+15;
int main(){
    long long m,s[N]={},right,left=0,mid,ans,c;
    int n;
    cin>>n>>m;
    for(int i=0;i<n;i++)cin>>s[i];
    right=*max_element(s,s+n);
    while(left<=right){
        c=0,mid=(left+right)/2;
        for(int i=0;i<n;i++)if(s[i]>mid)c+=s[i]-mid;
        if(c>=m)ans=mid,left=mid+1;
        else right=mid-1;
    }cout<<ans<<endl;
    return 0;
}