/* logical operators, relational operators, if,else statement

relational operators: >, <, >=, <=, ==, !=  same as in Python
logical operators:
and  &&  
or   ||
not  !

write a program that reads student grade, checks validity of the input
and prints the letter grade based on the rule:
90-100 	A
89-80 	B
79-70 	C
69-60 	D
<60  	F

*/
#include<stdio.h>
int main(){
	int grade;
	printf("enter grade\n");
	scanf("%d",&grade);
	if(grade>=0 && grade<=100){
	
		if(grade>=90)   //if(grade>=90 && grade<=100)
			printf("%d is A\n",grade);
		else if(grade>=80) //if(grade>=80 and grade<=89)
			printf("%d is B\n",grade);		
		else if(grade>=70)
			printf("%d is C\n",grade);
		else if(grade>=60)
			printf("%d is D\n",grade);
		else
			printf("%d is F\n",grade);

	}
	else{
		printf("%d invalid grade\n",grade);
	}
	return 0;

}