#define DECODE_PLUS

#include <stdio.h>
#include <ctype.h>

int main()
{
	int pos=0;
	char b;
	char out=0;
	int got=0;

	while (fread(&b, 1, 1, stdin)) {
		switch (got) {
			case 0:
				if (b == '%') {
					got=1;
					break;
				}
#ifdef DECODE_PLUS
				if (b == '+') {
					printf(" ");
					break;
				}
#endif
				printf("%c", b);
				break;
			case 1:
				b=tolower(b);
				if (!((b >= '0' && b <= '9') || (b >= 'a' && b <= 'z'))) {
					fprintf(stderr, "invalid input sequence at position %d\n", pos);
					got=0;
					break;
				}
				got=2;
				b-=48;
				if (b > 9)
					b-=39;
				out=b << 4;
				break;
			case 2:
				got=0;
				b=tolower(b);
				if (!((b >= '0' && b <= '9') || (b >= 'a' && b <= 'z'))) {
					fprintf(stderr, "invalid input sequence at position %d\n", pos);
					break;
				}
				b-=48;
				if (b > 9)
					b-=39;
				out|=b;
				printf("%c", out);
				break;
		}
		pos++;
	}
	return 0;
}