//package misc.ukiepc2025

fun main() {
	val rules = MutableList(readInt()) {
		val s = readln()
		if (s[2] == '<') s[0] to s[4] else s[4] to s[0]
	}
	val word = readln()
	val alphabet = List(26) { 'a' + it }
	val topSort = mutableListOf<Char>()
	repeat(alphabet.size) {
		val c = (alphabet - topSort.toSet()).firstOrNull { c ->
			rules.none { it.second == c }
		} ?: return println("IMPOSSIBLE")
		topSort.add(c)
		rules.removeIf { it.first == c || it.second == c }
	}
	println(word.toList().sortedBy { topSort.indexOf(it) }.joinToString(""))
}

private fun readInt() = readln().toInt()