//תרגיל 1
using System;
string Grade (double Ngrade){
string x = " ";
if (Ngrade>=90 && Ngrade<100 ){
x = "A";
}
else if (Ngrade>=80 && Ngrade<90){
x = "B";
else if (Ngrade>=70 && Ngrade<80){
x="C";
else if (Ngrade>=60 && Ngrade<70){
x="D";
else if (Ngrade>=0 && Ngrade<60){
x="F";
else {
return x;