//Do not declare variable marks.
//Write your code below this line.
var getGrade = function(input){
    if(input>90){
        console.log('AA');
    }else if (input>80 && input === 90){
        console.log('AB');
    }else if (input > 70 && input === 80){
        console.log('BB');
    }else if(input > 60 && input === 70){
        console.log('BC');
    }else if (input>50 && input === 60){
        console.log('CC');
    }else if(input>40 && input === 50){
        console.log('CD');
    }else if(input>30 && input === 40){
        console.log('DD');
    }else {
        console.log('FF');
    }
};

getGrade(100);