//Do not declare variable marks.
//Write your code below this line.
var score='100';

if(score>90)
{
    console.log('AA')
}
else if(score>80 && score<=90)
{
    console.log('AB')
}
else if(score>70 && score<=80)
{
    console.log('BB')
}
else if(score>60 && score<=70)
{
    console.log('BC')
}
else if(score>50 && score<=60)
{
    console.log('CC')
}
else if(score>40 && score<=50)
{
    console.log('CD')
}
else if(score>30 && score<=40)
{
    console.log('DD')
}
else if(score<=30)
{
    console.log('FF')
}
else
{
    console.log('No score');
}