#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>

using namespace std;
using namespace __gnu_pbds;

template<typename T>
ostream_iterator<T> oit(const string &s = " "){ return ostream_iterator<T>(cout,s.c_str()); }
inline auto rep(int l, int r) { return views::iota(min(l, r), r); }
inline auto rep(int n) { return rep(0, n); }
inline auto rep1(int l, int r) { return rep(l, r + 1); }
inline auto rep1(int n) { return rep(1, n + 1); }
inline auto per(int l, int r) { return rep(l, r) | views::reverse; }
inline auto per(int n) { return per(0, n); }
inline auto per1(int l, int r) { return per(l, r + 1); }
inline auto per1(int n) { return per(1, n + 1); }
#define A(a) begin(a),end(a)
inline auto len = ranges::ssize;

struct chash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }

    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};
template<typename T, typename U> using pb_map = gp_hash_table<T, U, chash>;
template<typename T> using pb_set = gp_hash_table<T, null_type, chash>;
#define K first
#define V second

using ll = long long;
using ld = long double;

using vi = vector<int>;
using vii = vector<vector<int>>;
typedef vector<ll> vll;
using pll = pair<ll,ll>;
using pii = pair<int,int>;

constexpr ll NN = 100, M = 1000000007, L = 20;


int dp[NN][NN][2][2];
string s;int n;
int rec(int l,int r,char lc,char rc){
    if(l>=r) return 0;
    int &state = dp[l][r][lc=='W'][rc=='W'];
    if(state not_eq -1) return state;

    state=0;
    set<int> st;
    for(int i : rep(l,r)){
        char c1 = (i==l ? lc : s[i]);
        char c2 = ((i+1)==r ? rc : s[i+1]);
        if(c1 not_eq c2){
            st.insert(rec(l,i,lc,c2)^rec(i+2,r,s[i+2],rc)); //i+1 eats i
            st.insert(rec(i+1,r,c1,rc)^rec(l,i-1,lc,(i ? s[i-1] : 'W')));//i eats i+1
        }
    }

    while(st.contains(state)) ++state;
    // cout << l << " " << r << " " << lc << " " << rc << endl;
    // cout << "\t" << state << endl;
    return state;
}


void run()
{
    cin >> n >> s;   s += "padding";
    vector<pii> v; int l = 0;
    for(int r : rep(n)){
        if(s[r]=='.' and s[l]!='.') v.emplace_back(l,r-1);
        if(s[r]=='.')l=r+1;
    } if(l<n) v.emplace_back(l,n-1);


    int nimber = 0;
    for(auto [l,r] : v){
        nimber ^= rec(l,r,s[l],s[r]);
    }
    if(nimber){
        vector<pii> ans;
        for(auto [l,r] : v){
            auto og = rec(l,r,s[l],s[r]);
            auto need = nimber^og;

            for(int i : rep(l,r)){
                if(s[i] != s[i+1]){
                    auto x1 = rec(l,i,s[l],s[i+1]);
                    auto x2 = rec(i+2,r,s[i+2],s[r]);
                    if((x1^x2)==need) ans.emplace_back(i+1,i);
                    x1 = rec(i+1,r,s[i],s[r]);
                    x2 = rec(l,i-1,s[l], (i ? s[i-1] : 'W') );
                    if((x1^x2)==need) ans.emplace_back(i,i+1);
                }
            }
        } ranges::sort(ans);
        cout << len(ans) << '\n';
        for(auto [x,y] : ans) cout <<x+1 << " " << y+1 << '\n';
    }else cout << "0\n";
}

int main()
{
    //KING OF THE WORLD...... U.W.T.B
    std::cin.tie(0);
    ios_base::sync_with_stdio(false);
    for(auto &v : dp) for(auto &vv : v) for(auto &vvv: vv) for(auto &x : vvv) x=-1;
    run();
}