module Main;

import BinaryHeap;
import BoolArray;
import CPLib.Arithmetic;
import CPLib.Bipartite;
import CPLib.Bits;
import CPLib.Convolution;
import CPLib.DSegtree;
import CPLib.Graph;
import CPLib.IO;
import CPLib.LDSegtree;
import CPLib.LSegtree;
import CPLib.MaxFlow;
import CPLib.Memoize;
import CPLib.MinCostFlow;
import CPLib.Misc;
import CPLib.Monoid;
import CPLib.Segtree;
import CPLib.String;
import CPLib.Trait;
import CPLib.TwoSat;
import CPLib.UnionFind;
import CPLib.ZP;
import HashMap;
import HashSet;

main : IO () = (
    let cK = *read_i;
    let cN = *read_i;
    let cN = cN + 1;
    let ps = calc_prime_list(cN);
    let ps = ps.to_iter.filter(|x| cK <= x.i64).map(i64).to_array;
    let hash : I64 -> I64 = |p| (
        let hash1 : I64 -> I64 = |p| (
            loop((0, p), |(sum, p)|
                if p == 0 { sum.break };
                let sum = sum + p % 10;
                let p = p / 10;
                (sum, p).continue
            )
        );
        loop(p, |p|
            if p < 10 { p.break };
            hash1(p).continue
        )
    );
    let hs = ps.map(hash);
    let mxi = loop(((0, 0), 0, 0, 0), |((mx, mxi), begin, end, flag)|
        let (end, flag) = loop((end, flag), |(end, flag)|
            if end >= hs.@size { (end, flag).break };
            let h = hs.@(end);
            if flag.bit_check(h) {
                (end, flag).break
            } else {
                let end = end + 1;
                let flag = flag.bit_set(h);
                (end, flag).continue
            }
        );
        let len = end - begin;
        let (mx, mxi) = if len >= mx {
            (len, begin)
        } else {
            (mx, mxi)
        };
        if end == hs.@size { mxi.break };
        let h = hs.@(begin);
        let flag = flag.bit_clear(h);
        let begin = begin + 1;
        ((mx, mxi), begin, end, flag).continue
    );
    let ans = ps.@(mxi);
    ans.to_string.println;;
    pure()
);