A leap year is exactly divisible by 4 except for century years (years ending with 00). The century year is a leap year only if it is perfectly divisible by 400.

## Example: Check Leap Year

```
# Program to check if the input year is a leap year or not
year = as.integer(readline(prompt="Enter a year: "))
if((year %% 4) == 0) {
if((year %% 100) == 0) {
if((year %% 400) == 0) {
print(paste(year,"is a leap year"))
} else {
print(paste(year,"is not a leap year"))
}
} else {
print(paste(year,"is a leap year"))
}
} else {
print(paste(year,"is not a leap year"))
}
```

**Output 1**

Enter a year: 1900 [1] "1900 is not a leap year"

**Output 2**

Enter a year: 2000 [1] "2000 is a leap year"

If a year is divisible by 4, 100 and 400, it's a leap year.

If a year is divisible by 4 and 100 but not divisible by 400, it's not a leap year.

If a year is divisible by 4 but not divisible by 100, it's a leap year.

If a year is not divisible by 1, it's not a leap year.

This logic is implemented in the above program using nested `if...else`

statement.