const result = [];

for(let i=1; i<=12; i++) {
    let day;
    switch(i) {
        case 2:
            day = 28;
            break;
        case 4:
        case 6:
        case 9:
        case 11:
            day = 30;
            break;
        default:
            day = 31;
            break;
    }
    for(let j=1; j<=day; j++){
        if((j < 10 && i === j) || 
        (j >= 10 && i === Number(j.toString().slice(0,1)) + Number(j.toString().slice(1,2)))) {
            result.push(`${i}月${j}日`);
        }
    }
}

console.log(result.length);