const fs = require('fs')
const stdin = fs.readFileSync('/dev/stdin', 'utf8')

const [n, s] = stdin.split('\n')

const N = Number(n)

const S = s.split('')

console.log(S)

let leftBlack = 0
let rightWhite = S.reduce((p, c) => {
  return p += c === '.' ? 1 : 0
}, 0)

const sum = S.map((v, i) => {
  leftBlack += v === '#' ? 1 : 0 
  rightWhite -= v === '.' ? 1 : 0
  return leftBlack + rightWhite
})

const min = Math.min(...sum)

console.log(min)