Mars Exploration 2

mars2.js

function main() {
    let S = readLine().match(/.{1,3}/g);
    
    let count = 0;
    
    for (let i in S) {
        if (S[i][0] !== 'S') {
            count++;
        }
        
        if (S[i][1] !== 'O') {
            count++;
        }
        
        if (S[i][2] !== 'S') {
            count++;
        }
    }
    
    console.log(count);
}