Codeforces Round #253 (Div. 2)——Borya and Hanabi

set<int> st[10];
int all = 1 << 10, ans = INF;

int change(char x)
{
    if (x == 'B') return 0;
    else if (x == 'Y') return 1;
    else if (x == 'W') return 2;
    else if (x == 'G') return 3;
    else return 4;          //R
}
void fun(int num, set<int> st[])
{
    int one = 0, t[10] = {0};
    for (int j = 1, ct = 0; j < all; j <<= 1, ct++)
        if (num & j)
        {
            one++;
            t[ct] = 1;
        }
    REP(i, 5) FF(j, 5, 10)
        if (t[i] && t[j])
        {
            st[i].erase(j);
            st[j].erase(i);
        }
    REP(i, 10)
        if (t[i] && st[i].size() == 1)
        {
            st[*(st[i].begin())].erase(i);
            st[i].clear();
        }
    int len = 0;
    REP(i, 5) len += st[i].size();
    if (len <= 1)
        ans = min(ans, one);
}
int main()
{
    int n;
    char x; int y;
    cin >> n;
    REP(i, n)
    {
        cin >> x >> y;
        st[change(x)].insert(y + 4);
        st[y + 4].insert(change(x));
    }
    FF(i, 0, all)
    {
        set<int> tt[10];
        REP(j, 10) tt[j] = st[j];
        fun(i, tt);
    }
    WI(ans);
    return 0;
}