<?php
	$k = trim(fgets(STDIN));
	$n = trim(fgets(STDIN));
	
	// create prime's list
	$prime = [];
	$hash = [];
	$bool = [];
	for($i = 0; $i < $n; $i++){
		$bool[$i] = false;
	}
	for($i = 2; $i <= $n; $i++){
		if($bool[$i]) continue;
		if($i >= $k){
			array_push($prime, $i);
			$hashTmp = $i;
			while($hashTmp > 9){
				$hashTmp = (string)$hashTmp;
				$hashTmp2 = 0;
				for($l = 0; $l < strlen($hashTmp); $l++){
					$hashTmp2 += (int)$hashTmp[$l];
				}
				$hashTmp = $hashTmp2;
			}
			array_push($hash, $hashTmp);
		}
		for($j = $i * $i; $j < $n; $j += $i){
			$bool[$j] = true;
		}
	}
	// create prime's list end
	
	$ans = $prime[0];
	$check = [];
	for($i = 0; $i < 10; $i++){
		$check[$i] = 0;
	}
	$begin = 0;
	$end = 0;
	do{
		$flag = true;
		$check[$hash[$end]] += 1;
		if($check[$hash[$end]] == 2){
			do{
				$check[$hash[$begin++]]--;
				$check[$hash[++$end]]++;
				$flag = true;
				for($m = 0; $m < 10; $m++){
					if($check[$hash[$m]] > 1){
						$flag = false;
						break;
					}
				}
				if($flag) break;
			}while($end < count($prime));
		}
		if($flag){
			$ans = $prime[$begin];
		}
		$end++;
	}while($end < count($prime));
	
	echo $ans."\n";
?>