C simple program doesn't work

Question

Hello everyone! I'm trying to learn C language and have this trouble:

Example code from book works as it should work:

#include <stdio.h>
/* печать таблицы температур по Фаренгейту
и Цельсию для fahr = 0, 20, ..., 300 */

main()
{
    int fahr, celsius;
    int lower, upper, step;

    lower = 0; /* нижняя граница таблицы температур */
    upper = 300; /* верхняя граница */
    step = 20;  /* шаг */

    fahr = lower;
    while (fahr <= upper) {
        celsius = 5 * (fahr-32) / 9;
        printf("%d\t%d\n", fahr, celsius);
        fahr = fahr + step;
    }
}

Output:

0 -17
20 -6
40 4
60 15
80 26
100 37
120 48
140 60
160 71
180 82
200 93
220 104
240 115
260 126
280 137
300 148

But code that I've written doesn't do anything!:

#include <stdio.h>

main() {
    int fahr, celsius, lower, upper, step;

    printf("Enter lower temperature:");
    scanf("%d", &lower);

    printf("Enter upper limit:");
    scanf("%d", &lower);

    printf("Enter step:");
    scanf("%d", &lower);

    fahr = lower;
    while (fahr <= upper) {
        celsius = 5 * (fahr-32) / 9;
        printf("%d\t%d\n", fahr, celsius);
        fahr = fahr + step;
    }
}

Output:

$ gcc fahr.c -o fahr.out
$ ./fahr.out
Enter lower temperature:0
Enter upper limit:300
Enter step:20
$

What's wrong?

Answer 1

Change this part ->

 printf("Enter upper limit:");
    scanf("%d", &lower);

    printf("Enter step:");
    scanf("%d", &lower);

to

 printf("Enter upper limit:");
    scanf("%d", &upper);

    printf("Enter step:");
    scanf("%d", &step);

Answer 2

All of your scanfs read the variable lower.

scanf("%d", &lower);

This is very typical when you copy and paste sections of code. Welcome to C we hope you grow to love it as much as the rest of us.