#include <bits/stdc++.h>
int n, m, lst[600005], nxt[600005];
bool a[600005];
char x;
std::vector<std::pair<int, int>> op;
void connect(int A, int B)
{
    lst[nxt[A] = B] = A;
}
int ap, bp, al, ar, bl, br;
void swap()
{
    op.push_back({ap, bp});
    int lstal = lst[al], lstbl = lst[bl], nxtar = nxt[ar], nxtbr = nxt[br];
    connect(lstal, bl);
    connect(lstbl, al);
    connect(ar, nxtbr);
    connect(br, nxtar);
    std::swap(al, bl);
    std::swap(ar, br);
}
signed main()
{
    std::ios::sync_with_stdio(false);
    std::cin >> n >> m;
    for (int i = 1; i <= n + n; ++i)
        std::cin >> x, a[i] = x == 'C';
    if (std::count(a + 1, a + 1 + n, true) > std::count(a + 1, a + 1 + n, false))
    {
        for (int i = 1; i <= n + n; ++i)
            a[i] ^= true;
    }
    for (int i = 1; i <= n; ++i)
    {
        nxt[i] = i == n ? 1 : i + 1;
        lst[i] = i == 1 ? n : i - 1;
    }
    for (int i = n + 1; i <= n + n; ++i)
    {
        nxt[i] = i == n + n ? n + 1 : i + 1;
        lst[i] = i == n + 1 ? n + n : i - 1;
    }
    ap = 1, bp = 1, al = 1, ar = m, bl = n + 1, br = n + m;
    for (int i = 1; i <= n; ++i)
    {
        // std::cout << ap << ' ' << bp << std::endl;
        // for (int i = al, j = 1; j <= n; ++j, i = nxt[i])
        //     std::cout << a[i];
        // std::cout << std::endl;
        // for (int i = bl, j = 1; j <= n; ++j, i = nxt[i])
        //     std::cout << a[i];
        // std::cout << std::endl;
        if (a[nxt[ar]])
        {
            while (a[bl])
            {
                bp = bp % n + 1;
                bl = nxt[bl];
                br = nxt[br];
            }
            swap();
            ap = ap % n + 1;
            al = nxt[al];
            ar = nxt[ar];
            swap();
        }
        else
        {
            ap = ap % n + 1;
            al = nxt[al];
            ar = nxt[ar];
        }
    }
    std::cout << op.size() << std::endl;
    for (auto i : op)
    {
        std::cout << i.first << ' ' << i.second << std::endl;
    }
    return 0;
}