export {};

type pair = [number, number]; // [value, index]

const input: string[] = require("fs").readFileSync(0).toString().trim().split('\n');
const [N, M]: number[] = [Number(input[0]), Number(input[2])];
let A: number[] = input[1].split(' ').map(Number);
let B: number[] = input[3].split(' ').map(Number);

const comparator = (a: pair, b: pair) => {
    if(a[0] === b[0]) return a[1] - b[1];
    return b[0]-a[0];
};

let pairA: pair[] = A.map((v,i)=>[v,i]);
let pairB: pair[] = B.map((v,i)=>[v,i]);

pairA.sort(comparator);
pairB.sort(comparator);

let subsequence: number[] = [];
let limitA = -1, limitB = -1;
let idxA = 0, idxB = 0;

while(idxA < N && idxB < M) {
    const [valA, posA]: number[] = pairA[idxA];
    const [valB, posB]: number[] = pairB[idxB];

    if(valA===valB) {
        if(posA > limitA && posB > limitB) {
            subsequence.push(valA);
            limitA = posA;
            limitB = posB;
            idxA++;
            idxB++;
        }
        else if(posA <= limitA) idxA++;
        else idxB++;
    }
    else if(valA > valB) idxA++;
    else idxB++;
}

console.log(subsequence.length);
if (subsequence.length !== 0) console.log(...subsequence);