Solve in Python:
Return the century of the input year. The input will always be a 4 digit string, so there is no need for validation. 

### Examples
```
"1999" --> "20th"
"2011" --> "21st"
"2154" --> "22nd"
"2259" --> "23rd"
"1124" --> "12th"
"2000" --> "20th"
```
def what_century(year):
    y = int(year)
    c, r = divmod(y, 100)
    if r:
        c += 1
    ones = c%10
    tens = (c//10)%10
    if tens == 1:
        suffix = "th"
    elif ones == 1:
        suffix = "st"
    elif ones == 2:
        suffix = "nd"
    elif ones == 3:
        suffix = "rd" 
    else:
        suffix = "th"
    return str(c)+suffix