R guess number game

s <- sample(0:9, 4, replace = FALSE)
while (TRUE) {
  g <- readline('Please input your guess! Guess number:')
  if (!grepl("\\d{4}", g)) {
    cat('You should input 4 digit number.')
    next
  }
  g <- strsplit(g, "")[[1]]
  cnt_a <- sum(g == s)
  cnt_b <- sum(g %in% s) - cnt_a
  if (all(g == s)) {
    cat('You are right!!!!!!!')
    break
  } else {
    cat(sprintf("%iA%iB", cnt_a, cnt_b))
  }
}