// ---------- begin input macro ---------- // reference: https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8 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, $t)).collect::>() }; ($iter:expr, chars) => { read_value!($iter, String).chars().collect::>() }; ($iter:expr, bytes) => { read_value!($iter, String).bytes().collect::>() }; ($iter:expr, usize1) => { read_value!($iter, usize) - 1 }; ($iter:expr, $t:ty) => { $iter.next().unwrap().parse::<$t>().expect("Parse error") }; } // ---------- end input macro ---------- fn run() { input! { n: usize, k: usize, s: bytes, } let mut cnt = vec![0; n + k + 1]; for (i, &c) in s.iter().enumerate() { if c == b'x' { cnt[i + 1] = 1; } } for i in (0..n).rev() { cnt[i] += cnt[i + 1]; } let mut right = vec![]; for i in 0..n { if i > 0 && s[i - 1] == b'x' { continue; } let w = k - (cnt[i + 1] - cnt[i + 1 + k]); right.push(w); } let n = right.len(); let mut dp = vec![false; n]; let mut lose = n + k + 1; for (i, &r) in right.iter().enumerate().rev() { if lose <= i + r { dp[i] = true; } else { lose = i; } } println!("{}", dp.iter().position(|p| !*p).unwrap()); } fn main() { run(); }