An algorithm is shown in the pseudocode below:

1  SET c1 TO 'London'
2  SET c2 TO 'Paris'
3  SET c3 TO 'Tokyo'
4  SET c4 TO 'New York'
5
6  SEND ('Enter a city: ') TO DISPLAY
7  RECEIVE target FROM (STRING) KEYBOARD
8
9  IF (c1 = target) THEN
10 SEND ('Match') TO DISPLAY
11 ELSE
12 IF (c2 = target) THEN
13 SEND ('Match') TO DISPLAY
14 ELSE
15 IF (c3 = target) THEN
16 SEND ('Match') TO DISPLAY
17 ELSE
18 IF (c4 = target) THEN
19 SEND ('Match') TO DISPLAY
20 END IF
21 END IF
22 END IF
23 END IF

Explain one improvement to this algorithm that will reduce the number of variables required and will enable it to work with any number of cities.