import sys, pprint, string arr = [] alpha=list(string.ascii_letters) values_part1=[] values_part2=[] with open(sys.argv[1]) as f: for l in f: line=l.split()[0] first, second = line[:len(line)//2],line[len(line)//2:] shared=list(set(first)&set(second))[0] index=alpha.index(shared)+1 values_part1.append(index) arr.append([line,first,second,shared,int(index)]) print(sum(values_part1)) for i in range(0,len(arr),3): shared=list(set(arr[i][0])&set(arr[i+1][0])&set(arr[i+2][0]))[0] values_part2.append(int(alpha.index(shared)+1)) print(sum(values_part2))