Word Equalizing

You are given two words $x$ and $y$, together with a series of $k$ words $(w_1, w_2, \ldots, w_k)$. The operation $w \oplus w_i$ appends the series word $w_i$ ($1 \le i \le k$) to the end of the word $w$ (concatenation): it writes $w_i$ immediately after $w$.

By appending series words to the ends of $x$ and $y$ (using any word as many times as you like, on either word), decide whether the two words can be made identical. If it is possible, output the minimum number of $\oplus$ operations required; otherwise output NIE ("no" in Polish).

For example, the words abba and ab can be equalized using the series baaabad, aa, badccaa, cc: append aa and badccaa to abba, and append baaabad, then cc, then aa to ab. Both become abbaaabadccaa, using $2 + 3 = 5$ operations in total.

The first line contains a positive integer $k$ ($1 \le k \le 40$), the length of the series. The second and third lines contain the descriptions of $x$ and $y$. The next $k$ lines contain the descriptions of $w_1, w_2, \ldots, w_k$, one per line. Each description consists of the word's length (a natural number) and the word itself, separated by a single space. Every word consists only of lowercase letters a to z and has length at most 2,000. The total length of all given words is at most 5,000.

If $x$ and $y$ can be equalized, output the minimum number of $\oplus$ operations (a nonnegative integer). Otherwise, output NIE.