#include <bits/stdc++.h>

using namespace std;
using ll = long long;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int n;
    cin >> n;

    string s;
    cin >> s;

    vector<pair<int, int>> ans;

    while (size(s) > 1) {
        for (int i = 1; i < size(s); ++i) {
            if (s[i] == s[i - 1]) {
                int j = i;
                while (j < size(s) && s[i] == s[j]) {
                    j += 1;
                }
                int len = j - (i - 1);
                while (len > 3) {
                    ans.push_back({i, 2});
                    len -= 2;
                }
                ans.push_back({i, len});
                s.erase(s.begin() + i - 1, s.begin() + j);
                break;
            }
        }
    }

    if (!s.empty()) {
        cout << -1 << '\n';
        return 0;
    }

    cout << size(ans) << '\n';

    for (auto [l, r] : ans) {
        cout << l << " " << r << '\n';
    }

    return 0;
}