#include <iostream>
#include <string>
#include <vector>
#include <queue>
#include <stack>
#include <map>
#include <algorithm>
#include <numeric>
#include <functional>
#include <set>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <cctype>
#include <climits>
#include <fstream>
#include <time.h>

#define ll long long
#define FOR(i,a,b) for(int i=(a);i<((int)b);++i)
#define REP(i,n) FOR(i,0,n)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define DUMP(x)  cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0L)
#define EPS 1e-14

using namespace std;

struct ColorfulRoad {
    string road;
    int getMin(string _road) {
        road = _road;
        vector<int> v(road.size(), INT_MAX);
        v[0] = 0;
        map<char, char> next = { { 'R', 'G' }, { 'G', 'B' }, {'B', 'R'} };
        REP(i, road.size()) {
            FOR(j, i + 1, road.size()) {
                if (road[j] == next[road[i]] && v[i] != INT_MAX) {
                    v[j] = min(v[j], v[i] + (j - i) * (j - i));
                }
            }
        }

        return (v[v.size() - 1] == INT_MAX) ? -1: v[v.size() - 1];
    }
};