#include <stdio.h>
#include <string.h>

#define BAD_ARGS 1
int main(int argc, char *argv[]) {
	static char buf[30000000];
	int error = BAD_ARGS;
	if (argc > 1) {
		char *p = buf, *q = buf+1; // elves
		char *r = buf+2; // next recipe score
		char score;
		error = 0;
		*p = '3';
		*q = '7';
		do {
			score = *p + *q - '0';
			if (score <= '9') *r++ = score;
			else {
				*r++ = '1';
				*r++ = score - 10;
			}
			p += *p - '0' + 1;
			q += *q - '0' + 1;
			while (p >= r) p -= (r - buf);
			while (q >= r) q -= (r - buf);
		}
		while (r - buf < sizeof buf - 2);
		
		r = strstr(buf, argv[1]);
		if (r) printf("%d\n", r - buf);
		else puts("∞");
	}
	return error;
}