#include <unistd.h>

int main() {
    char a;
    char b;
    char c;

    a = '0';
    while(a <= '9')
    {
        b = a+1;
        while(b <= '9')
        {
            c = b+1;
            while(c <= '9')
            {
                write(1, &a, 1);
                write(1, &b, 1);
                write(1, &c, 1);  
                write(1, "\n", 1);
                c++;
            }
            b++;
        }
        a++;
    }
    return 0;
}