Find First Character That Repeats

Create a function that takes a string and returns the first character that repeats. If there is no repeat of a character, then return "-1".

Examples

first_repeat("legolas") ➞ "l"

first_repeat("Gandalf") ➞ "a"

first_repeat("Balrog") ➞ "-1"

first_repeat("Isildur") ➞ "-1"

Notes

Tests are case sensitive.