#include <stdio.h>

char flipBit(char c);

char flipBit(char c) {
    if (c == '0')
        return '1';
    else 
        return '0';
}
    
int main() {
                        
						char binaryNumber[] = { '0','0','0','0',0 };
						int slot1,slot2,slot3,slot4;


						for (slot1=0 ; slot1 < 2 ; slot1++) {
							printf("\n%s",binaryNumber);
							for (slot2 =1 ; slot2 < 2 ; slot2++) {
								binaryNumber[slot2] = flipBit(binaryNumber[slot2]);
								
								printf("\n%s",binaryNumber);

								for (slot3=2 ; slot3 < 3 ; slot3++) {
									binaryNumber[slot3] = flipBit(binaryNumber[slot3]);
                                    printf("\n%s",binaryNumber);


									for (slot4=3 ; slot4 < 4 ; slot4++) {
										binaryNumber[slot4] = flipBit(binaryNumber[slot4]);
										printf("\n%s",binaryNumber);
									}
								}

							}
							binaryNumber[slot1] = flipBit(binaryNumber[slot1]);
                            printf("\n");
						}
}