Intro to visual basic question

each time the user input a city name increase the counter by one and compare with the last entred city to know the max and save it in a variable; simple for loop finishs this.

simple example:
dim counter as integer
dim maxLen,tmp as string

maxLen=0
while(exitEvent){
tmp = inputbox("Enter the city name:")
if len(tmp) > maxLen then maxLen = tmp
counter = counter + 1
}