information-processing-1_6th-class/programs/abs/main.c

#include <stdio.h>

int main(void) {
    int x, y;

    printf("Input integer: ");
    scanf("%d", &x);

    y = x;

    if (y < 0)
        y = -y;
    
    printf("Absolute value of %d is %d.\n", x, y);

    return 0;
}