#include <bits/stdc++.h>
#include "Anna.h"

using namespace std;

namespace Anna {
    int v[1 << 20];

    pair<string, int> anna(int n, string S) {
        if (n <= 28) {
            string T;
            for (int i = 0; i < n; ++i) {
                T += (S[i] == 'R' ? 'G' : 'R');
            }
            return {T, n};
        }
        mt19937 rnd;
        for (int i = 0; i < n; ++i) v[i] = rnd() % 3;
        string T;
        for (int i = 0; i + 1 < n; i += 2) {
            int ok = 0;
            for (int j = 0; j < 3 && !ok; ++j) {
                for (int k = 0; k < 3; ++k) {
                    if ((j + k) % 3 != v[i] || "RGB"[j] == S[i] || "RGB"[k] == S[i + 1]) {
                        continue;
                    }
                    T += "RGB"[j];
                    T += "RGB"[k];
                    ok = 1;
                    break;
                }
            }
        }
        if (n & 1) {
            T += (S.back() == 'R' ? 'G' : 'R');
        }
        return {T, 28};
    }
}

pair<string, int> anna(int n, string S) {
    return Anna::anna(n, S);
}

#include <bits/stdc++.h>
#include "Bruno.h"

using namespace std;

namespace Bruno {
    int n, m, v[1 << 20];

    map<string, int> M;

    void init(int _n, int _m) {
        n = _n, m = _m;
        mt19937 rnd;
        for (int i = 0; i < n; ++i) v[i] = rnd() % 3;
        for (int i = 0; i < n; i += 2) {
            string o;
            for (int j = 0; j < 14; ++j) {
                o += "012"[v[i + j * 2]];
                if (j == 12 || j == 13) M[o] = i + 1;
            }
        }
    }

    int tr(char c) {
        return (c == 'R' ? 0 : (c == 'G' ? 1 : 2));
    }

    int bruno(string s) {
        if (n == m) return 1;
        for (int i = 0; i < 2; ++i) {
            string T;
            for (int j = i; j + 1 < m; j += 2) {
                T += "012"[(tr(s[j]) + tr(s[j + 1])) % 3];
            }
            if (M.count(T)) return M[T] - i;
        }
        return -1;
    }
}

void init(int n, int l) {
    Bruno::init(n, l);
}

int bruno(string s) {
    return Bruno::bruno(s);
}