TIOJ 1208

//TIOJ 1208
/******************************************************************************

                              Online C++ Compiler.
               Code, Compile, Run and Debug C++ program online.
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*******************************************************************************/

#include <bits/stdc++.h>
using namespace std;

int arr[20001], sum[20001];
int n,k;

int msort(const int lhs, const int rhs, const int val){
    if(lhs == rhs-1)return (val <= sum[lhs])? 1 : 0;
    int mid = (lhs + rhs) / 2;
    int ret = msort(lhs, mid, val) + msort(mid, rhs, val);
    vector<int> left, right;
    for(int i = lhs; i < mid; ++i)left.emplace_back(sum[i]);
    for(int i = mid;  i < rhs; ++i)right.emplace_back(sum[i]);
    for(int i = 0, j = 0; i < left.size(); ++i){
        while(j < right.size() && val > right[j] - left[i])++j;
        ret += right.size() - j;
    }
    for(int i = 0, j = 0; i < left.size(); ++i){
        while(j < right.size() && left[i] > right[j]){
            sum[lhs+i+j] = right[j];
            ++j;
        }
        sum[lhs+i+j] = left[i];
    }
    return ret;
}

int cnt(int val){
    for(int i = 1; i <= n; ++i)sum[i] = sum[i-1] + arr[i];
    return msort(1, n+1, val);
}

int main(){
    while(cin >> n >> k){
        if(n == 0 && k == 0)break;
        for(int i = 1; i <= n; ++i)cin >> arr[i];
        int big = 2e9, small = -2e9;
        while(big >= small){
            int mid = (big+small) / 2;
            if(cnt(mid) < k)big = mid - 1;
            else small = mid + 1;
        }
        cout << big << '\n';
    }
    return 0;
}