import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Palindromes {

    public static void main(String[] args) throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        char[] lineup = in.readLine().toCharArray();
        int[] gs = new int[lineup.length];
        int amountG = 0;
        for (int j = 0; j < lineup.length; j++) {
            if (lineup[j] == 'G') {
                gs[amountG] = j;
                amountG++;
            }
        }
        long answer = 0;
        for (int leftCenter = 0; leftCenter < amountG; leftCenter++) {
            for (int rightCenter = leftCenter; rightCenter <= leftCenter + 1 && rightCenter < amountG; rightCenter++) {
                long[] e = new long[2 * lineup.length];
                long d = 0;
                long F = 0;

                for (int k = 0; leftCenter - k >= 0 && rightCenter + k < amountG; k++) {
                    int uk = gs[leftCenter - k];
                    int uk1 = leftCenter - k == 0 ? -1 : gs[leftCenter - (k + 1)];
                    int vk = gs[rightCenter + k];
                    int vk1 = rightCenter + (k + 1) == amountG ? lineup.length : gs[rightCenter + (k + 1)];

                    if (uk < vk) {
                        e[uk + vk] += 2;
                        d++;
                    }

                    for (int l = uk; l > uk1; l--) {
                        for (int r = vk; r < vk1; r++) {
                            if (leftCenter == rightCenter) {
                                if ((r - l) % 2 == 0) {
                                    answer += F + ((long) Math.abs(((r + l) / 2) - gs[leftCenter]));
                                } else {
                                    answer--;
                                }
                            } else {
                                answer += F;
                            }
                            F += d;
                            d += e[l + r + 1];
                        }

                        for (int r = vk1; r > vk; r--) {
                            d -= e[l + r];
                            F -= d;
                        }

                        d -= e[l + vk];
                        F -= d;
                    }

                    for (int r = vk; r < vk1; r++) {
                        F += d;
                        d += e[uk1 + r + 1];
                    }
                }
            }
        }
        System.out.println(answer);
    }
}