#include <bits/stdc++.h>
using namespace std;
#define int long long
#define mp make_pair
#define inf 1e9
#define pii pair <int, int>
const int mod = 1e9 + 7;
inline int read () {
	int x = 0, f = 1;
	char ch = getchar ();
	while (ch < '0' || ch > '9') f = ((ch == '-') ? -1 : f), ch = getchar ();
	while (ch >= '0' && ch <= '9') x = x * 10 + ch - '0', ch = getchar ();
	return x * f;
}
inline void write (int x) {
	if (x < 0) x = -x, putchar ('-');
	if (x >= 10) write (x / 10);
	putchar (x % 10 + '0');
}
int n;
char ch[1000005];
int tot;
vector <pii> Ans;
vector <int> a;
int f[1000005][3], pre[1000005][3];
void print0(int fr, int x) {
	if(x & 1) Ans.push_back(mp(fr, 3)), x -= 3;
	while(x >= 2) Ans.push_back(mp(fr, 2)), x -= 2;
}
void print1(vector <int> bas) {
	int mid = (int)bas.size() / 2, rk = 0;
	for(int i = 0; i < mid; i++) rk += bas[i];
	print0(rk + 1, bas[mid]);
	for(int i = 1; i <= mid; i++) {
		rk -= bas[mid-i];
		print0(rk + 1, bas[mid-i] + bas[mid+i]);
	}
}
void print2(vector <int> bas) {
	int mid = (int)bas.size() / 2, rk = 0;
	int l = mid, r = mid;
	while(bas[l] < 2) l--;
	while(bas[r] < 2) r++;
	for(int i = 0; i < l; i++) rk += bas[i];
	print0(rk + 1, bas[l]);
	for(int i = 1; i < r - mid; i++) {
		rk -= bas[l-i];
		print0(rk + 1, bas[l-i] + bas[l+i]);
	}
	vector <int> lst(bas.begin(), bas.begin() + l - r + mid);
	lst.push_back(bas[l-r+mid] + bas[l+r-mid]);
	lst.insert(lst.end(), bas.begin() + l + r - mid + 1, bas.end());
	print1(lst);
}
int tag[1000005];
signed main () {
//	freopen (".in", "r", stdin);
//	freopen (".out", "w", stdout);
	n = read();
	scanf("%s", ch + 1);
	a.push_back(1);
	for(int i = 2; i <= n; i++) {
		if(ch[i] != ch[i-1]) a.push_back(1);
		else a.back()++;
	}
	tot = (int)a.size();
	if(tot & 1) {
		if(a[tot/2] >= 2) print1(a);
		else {
			int mx = 0, s = 0;
			for(auto x : a) {
				if(x < 2) s++;
				else s = 0;
				mx = max(mx, s);
			}
			if(mx < tot / 2) print2(a);
			else return printf("-1\n") & 0;
		}
	}
	else {
		int mx = 0, s = 0;
		for(int i = (int)a.size() - 1; i >= 0; i--) {
			if(a[i] < 2) s++;
			else s = 0;
			mx = max(mx, s);
			if(i & 1) tag[i] = (mx < ((int)a.size() - i)  / 2 || a[((int)a.size()+i)/2] >= 2);
		}
		mx = 0, s = 0;
		for(int i = 0; i < (int)a.size(); i++) {
			if(a[i] < 2) s++;
			else s = 0;
			mx = max(mx, s);
			if(!(i & 1) && tag[i+1] && (mx < i / 2 || a[i/2] >= 2)) {
				vector<int> s1(a.begin(), a.begin() + i + 1), s2(a.begin() + i + 1, a.end());
				if(s1[(int)s1.size()/2] >= 2) print1(s1);
				else print2(s1);
				if(s2[(int)s2.size()/2] >= 2) print1(s2);
				else print2(s2);
				break;
			}
			if(i == (int)a.size() - 1) return printf("-1\n") & 1;
		}
	}
	write((int)Ans.size()), putchar('\n');
	for(auto x : Ans) write(x.first), putchar(' '), write(x.second), putchar('\n');
	return 0;
}
/*
10
BBABBAABAB
*/