# Print prime numbers from 1 to N in reverse order

Input number n till which prime numbers are calculated and displayed in reverse order

Input : number 30
Output : 29 23 19 17 13 11 7 5 3 2

## Algorithm

START
Step 1 -> declare variables as n, I, j, flag to 0 as int
Step 2 -> input number in n
Step 3 -> Loop For from i to n and i>1 and i—
Step 3.1 ->. Inner loop for from j to i/2 and j>=1 and j—
Statement If %j==0 && j!=1
Set flag=0
Break
End IF
Else
Flag=1
End Else
Step 3.2 -> end inner Loop For
Step 4 -> statement IF to check flag=1
Print i
End IF
Step 5 -> End outer For
STOP

## Example

#include <stdio.h>
int main(int argc, char const *argv[]) {
int n, i, j, flag=0;
printf("Enter a number");
scanf("%d", &n);
for(i=n; i>1; i--) {
for (j = i/2; j >= 1; j--) {
if(i%j==0 && j!=1) {
flag = 0;
break;
}
else
flag = 1;
}
if(flag == 1) {
printf("%d ", i);
}
}
return 0;
}

## Output

If we run the above program then it will generate the following output

Enter a number
30
29 23 19 17 13 11 7 5 3 2