NR %3 == 1 { split($0, arr, "") 
	for (a in arr) {
		A[arr[a]]=1
	}
}
NR %3 == 2 { split($0, arr, "") 
	for (a in arr) {
		B[arr[a]]=1
	}
}
NR %3 == 0 {
	split($0, arr, "")
	for (a in arr) {
		c = arr[a]
		if ((c in A) && (c in B)) {
			comm = c
		}
	}
	i = index("abcdefghijklmnopqrstuvwxyz", comm)
	j = index("ABCDEFGHIJKLMNOPQRSTUVWXYZ", comm)+26
	S += i > 0 ? i : j
	delete A
	delete B
}
END { print S}