func romanToInt(s string) int {
    // rune to their integer values
    romanValues := map[rune]int{
        'I': 1,
        'V': 5,
        'X': 10,
        'L': 50,
        'C': 100,
        'D': 500,
        'M': 1000,
    }
    
    result := 0
    prevValue := 0
    
    // iterate over each character (rune) in the string
    for _, char := range s {
        // integer value for the current symbol
        currentValue := romanValues[char]
        
        // value to the result
        result += currentValue
        
        // handle a subtraction case
        if currentValue > prevValue {
            // if current value is greater than previous value,
            // subtract twice the previous value:
            // once to cancel the previous addition, and once for the actual subtraction
            result = result - (2 * prevValue)
        }
        
        // next iteration
        prevValue = currentValue
    }
    
    return result
}