#include <stdio.h>

char str[] = "POLITEKNIK";
int strLength = sizeof(str) - 1;

void main() {
    char reverse = 'x';
    
    for (int i = 0, y = strLength; i < strLength; i++) {
        for (int j = 0; j < y; j++) {
            printf("%c", str[j]);
        }

        printf("\n");

        if (reverse == 'x')
            y--;
        else if (reverse == 'y')
            y++;

        if (i == (strLength - 1) && reverse == 'x')
            i = 0, reverse = 'y', y = 2;
    }
}