public class RedAndGreen {
    public int minPaints(String row) {
        int totalRedCount = 0;
        for (char c : row.toCharArray()) {
            if (c == 'R') {
                totalRedCount++;
            }
        }

        int minRepaints = totalRedCount;
        int index = 0;
        int currentRedCount = 0;
        for (char c : row.toCharArray()) {
            if (c == 'R') {
                currentRedCount++;
            }
            int currentGreenCount = index - currentRedCount + 1;
            int remainingRedCount = totalRedCount - currentRedCount;
            int repaints = currentGreenCount + remainingRedCount;
            if (repaints < minRepaints) {
                minRepaints = repaints;
            }
            index++;
        }
        return minRepaints;
    }
}