#include <stdio.h>

f(n,p)char*p;{for(p+=n-1;isalnum(*p)|*p==95&&n--;--p);for(;isalnum(*++p)|*p==95;putchar(*p));}

int main(void) {
	f(5,"abc d_f ghi");
	puts("");
	f(8,"ab     cd");
	return 0;
}