#include <stdio.h>
#include <unistd.h>
#include <signal.h>
#include <sys/types.h>

int param=0;
void shandler( int k )
{
    param = 1;
}

int main()
{
    int k = fork();
    if( k > 0 )
    {
        printf( "1\n" );
        kill( k, SIGUSR1 );
    }
    if( k < 0 )
        printf( "false" );
    if( k == 0 )
    {
        signal( SIGUSR1, shandler );
        for( ; param != 1; );
        printf( "2\n" );
        param = 0;
        kill( getppid(), SIGUSR1 );
    }
    if( k > 0 )
    {
        signal( SIGUSR1, shandler );
        for( ; param != 1; );
        printf( "3\n" );
        param = 0;
        kill( k, SIGUSR1 );
    }
    if( k == 0 )
    {
        signal( SIGUSR1, shandler );
        for( ; param != 1; );
        printf( "4\n" );
    }
    return 0;
}