'use strict';

const fs = require('fs');

process.stdin.resume();
process.stdin.setEncoding('utf-8');

let inputString = '';
let currentLine = 0;

process.stdin.on('data', inputStdin => {
    inputString += inputStdin;
});

process.stdin.on('end', _ => {
    inputString = inputString.replace(/\s*$/, '')
        .split('\n')
        .map(str => str.replace(/\s*$/, ''));

    main();
});

function readLine() {
    return inputString[currentLine++];
}

// Solution start

function getColorFreq(bugs) { // :Object{color:count, ...}
    return bugs.split("").reduce(
        (a, b) => {
            a[b] = (a[b] | 0) + 1;
            return a;
        }, {}
    );
}

function onlySpaces(bugs) { // :Boolean
    return bugs.match(/^_+$/g) != null;
}

function alreadyHappy(bugs) { // :Boolean
    if (onlySpaces(bugs)) return true;

    const len = bugs.length;
    if (len < 2 ||
        bugs[0] !== bugs[1] ||
        bugs[len - 1] !== bugs[len - 2]) return false;

    for (let i = 1; i < len - 2; ++i) {
        if (
            bugs[i] !== "_" &&
            bugs[i] !== bugs[i - 1] &&
            bugs[i] !== bugs[i + 1]
        ) return false;
    }
    return true;
}

function canBeHappy(bugs) { // :Boolean
    const freq = getColorFreq(bugs);
    for (const color in freq) {
        if (color !== '_' && freq[color] < 2)
            return false;
    }
    return freq['_'] > 0;
}

// Complete the happyLadybugs function below.
function happyLadybugs(bugs) {
    return alreadyHappy(bugs) || canBeHappy(bugs) ? "YES" : "NO";
}

function tests() {

    console.assert(onlySpaces("_")     === true);
    console.assert(onlySpaces("_____") === true);
    console.assert(onlySpaces("_____") === true);
    console.assert(onlySpaces("A____") === false);
    console.assert(onlySpaces("__A__") === false);
    console.assert(onlySpaces("____A") === false);

    const freq = getColorFreq("ABCD_BCD_CD_D");
    console.assert(freq['A'] === 1);
    console.assert(freq['B'] === 2);
    console.assert(freq['C'] === 3);
    console.assert(freq['D'] === 4);
    console.assert(freq['_'] === 3);

    console.assert(alreadyHappy("BBCCAA")  === true);
    console.assert(alreadyHappy("BB")      === true);
    console.assert(alreadyHappy("BBCC_AA") === true);
    console.assert(alreadyHappy("A")       === false);
    console.assert(alreadyHappy("BBC_CAA") === false);
    console.assert(alreadyHappy("BCCAAB")  === false);
    console.assert(alreadyHappy("BCC_AAB") === false);
}

function main() {

    tests();

    const ws = fs.createWriteStream(process.env.OUTPUT_PATH);

    const g = parseInt(readLine(), 10);

    for (let gItr = 0; gItr < g; gItr++) {
        const n = parseInt(readLine(), 10);

        const b = readLine();

        let result = happyLadybugs(b);

        ws.write(result + "\n");
    }

    ws.end();
}