let i = require('fs').readFileSync('/dev/stdin', 'utf8').split('\n').slice(0, -1)
let n = i[0].split(' ')
let s = i[1].split('')
let t = []
for (let c = 0; c < s.length; c++) {
  if (s[c] === '(') t.push(c)
  else {
    let x = t.pop()
    if (x+1 == n[1]) {
      console.log(c+1)
      break
    } else if (c+1 == n[1]) {
      console.log(x+1)
      break
    }
  }
}