def computegrade(score):
    if(float(score)>=1.0 or float(score)<=0.0):
        return 'Bad Score'
    if float(score)==0.9:
        return 'A'
    elif float(score)==0.8:
        return 'B'
    elif float(score)==0.7:
        return 'C'
    elif float(score)==0.6:
        return 'D'
    elif float(score)<0.6:
        return 'F'