//https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8 より
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, bytes) => {
        read_value!($iter, String).bytes().collect::<Vec<u8>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

//

fn run() {
    input! {
        n: usize,
        k: usize,
        a: [u64; n],
    }
    let mut b = vec![];
    b.extend_from_slice(&a);
    b.extend_from_slice(&a);
    let b = b;
    let valid = |m: u64| -> bool {
        let mut dp = vec![2 * n; 2 * n + 1];
        let mut r = 0;
        let mut sum = 0;
        for i in 0..(2 * n) {
            while r < 2 * n && sum < m {
                sum += b[r];
                r += 1;
            }
            dp[i] = r;
            sum -= b[i];
        }
        let mul = |a: &[usize], b: &[usize]| -> Vec<usize> {
            let mut c = vec![0; a.len()];
            for (i, a) in a.iter().enumerate() {
                c[i] = b[*a];
            }
            c
        };
        let mut t = (0..=(2 * n)).collect::<Vec<_>>();
        let mut s = dp;
        let mut k = k;
        while k > 0 {
            if k & 1 == 1 {
                t = mul(&t, &s);
            }
            s = mul(&s, &s);
            k >>= 1;
        }
        let mut ok = false;
        for (i, t) in t.iter().enumerate().take(n) {
            ok |= *t - i <= n;
        }
        ok
    };
    let mut ok = 1;
    let mut ng = a.iter().sum::<u64>() + 1;
    while ng - ok > 1 {
        let mid = (ok + ng) / 2;
        if valid(mid) {
            ok = mid;
        } else {
            ng = mid;
        }
    }
    println!("{}", ok);
}

fn main() {
    run();
}