// practice wdg 07
#include <stdio.h>
#include <string.h>

void swapEnd(char A[], char B[] ) 
{
    int aLen = strlen(A);
    int bLen = strlen(B);
    if(aLen==0 || bLen==0)
        return;
    char temp = A[aLen-1];
    A[aLen-1] = B[bLen-1];
    B[bLen-1] = temp;
}

int main(void) 
{
  char A[] = "cat";
  char B[] = "book";
  printf("%s %s became ", A, B);
  swapEnd(A,B);
  printf("%s %s\n", A, B);
  return 0;
}