gcc - C simple program doesn't work -

hello everyone! i'm trying learn c language , have trouble:

example code book works 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 i've written doesn't 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?

all of scanfs read variable lower.

scanf("%d", &lower); 

this typical when copy , paste sections of code. welcome c hope grow love as rest of us.