#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/types.h>
#include <pthread.h>


// prototipo de funciones
void f_hilo1(void) ;
void f_hilo2(void) ;

char letraminus = 'a' ;
char letramayus = 'B' ;

pthread_mutex_t m1 = PTHREAD_MUTEX_INITIALIZER ;
pthread_mutex_t m2 = PTHREAD_MUTEX_INITIALIZER ;

int main(int argc, char **argv) 
{

	pthread_t hilo1;
	pthread_t hilo2;

        pthread_mutex_lock(&m2) ;

	pthread_create(&hilo1,NULL,(void *)f_hilo1,NULL);
        pthread_create(&hilo2,NULL,(void *)f_hilo2,NULL);
		
	pthread_join(hilo1,NULL);
        pthread_join(hilo2,NULL);

        printf("\n");
	
        exit(0);
}


void f_hilo1(void) 
{  
  while(letraminus <= 'z')
  {
         pthread_mutex_lock(&m1);
//          printf("%c",letraminus);
          printf("%c\n",letraminus);
    //      sleep(1) ;
         pthread_mutex_unlock(&m2);
        letraminus+=2;
  }
}

void f_hilo2(void) 
{  
  while(letramayus <= 'Z')
  {
        pthread_mutex_lock(&m2);
        //    printf("%c",letramayus);
         printf("%c\n",letramayus);   
        letramayus+=2;
        pthread_mutex_unlock(&m1);
  }
}