```ts
export function firstUnbalanced(input: string): number {
  const stack: { char: string; index: number }[] = [];
  const openingBrackets = ['(', '[', '{'];
  const closingBrackets = [')', ']', '}'];
  
  for (let i = 0; i < input.length; i++) {
    const char = input[i];
    
    if (openingBrackets.includes(char)) {
      stack.push({ char, index: i });
    } else if (closingBrackets.includes(char)) {
      const matchingOpening = openingBrackets[closingBrackets.indexOf(char)];
      
      if (stack.length === 0 || stack[stack.length - 1].char !== matchingOpening) {
        return i;
      }
      
      stack.pop();
    }
  }
  
  // If there are still unclosed brackets, return the index of the earliest unclosed one
  if (stack.length > 0) {
    return stack[0].index;
  }
  
  return -1;
}
```