#include <unistd.h>

int main() {
    char digit[3];
    digit[0] = '0';
    digit[1] = '0';
    digit[2] = '0';

    while (digit[0] <= '9') {
        while (digit[1] <= '9') {
            while (digit[2] <= '9') {
                if((digit[0] != digit[1]) || (digit[1] != digit[2]) || (digit[0] != digit[2]))
                    write(1, &digit[0], 1);
                    write(1, &digit[1], 1);
                    write(1, &digit[2], 1);
                    write(1, "\n", 1);
                    digit[2]++;
            }
            digit[1]++;
        }
        digit[0]++;
    }

    return 0;
}