#include <bits/stdc++.h>
using namespace std;
#define rep(i, n)  for(long long i=0;i<(long long)(n);i++)
#define REP(i,k,n) for(long long i=k;i<(long long)(n);i++)
#define pb emplace_back
#define lb(v,k) (ll)(lower_bound(all(v),(k))-v.begin())
#define ub(v,k) (ll)(upper_bound(all(v),(k))-v.begin())
#define fi first
#define se second
#define pi M_PI
#define PQ(T) priority_queue<T>
#define SPQ(T) priority_queue<T,vector<T>,greater<T>>
#define dame(a) {out(a);return 0;}
#define decimal cout<<fixed<<setprecision(15);
#define all(a) a.begin(),a.end()
#define rsort(a) {sort(all(a));reverse(all(a));}
#define dupli(a) {sort(all(a));a.erase(unique(all(a)),a.end());}
#define popcnt __builtin_popcountll
typedef long long ll;
typedef pair<ll,ll> P;
typedef tuple<ll,ll,ll> PP;
typedef tuple<ll,ll,ll,ll> PPP;
using vi=vector<ll>;
using vvi=vector<vi>;
using vvvi=vector<vvi>;
using vvvvi=vector<vvvi>;
using vp=vector<P>;
using vvp=vector<vp>;
using vb=vector<bool>;
using vvb=vector<vb>;
const ll inf=1001001001001001001;
const ll INF=1001001001;
const ll mod=998244353;
const double eps=1e-10;
template<class T> bool chmin(T&a,T b){if(a>b){a=b;return true;}return false;}
template<class T> bool chmax(T&a,T b){if(a<b){a=b;return true;}return false;}
template<class T> void out(T a){cout<<a<<'\n';}
template<class T> void outp(T a){cout<<'('<<a.fi<<','<<a.se<<')'<<'\n';}
template<class T> void outvp(T v){rep(i,v.size())cout<<'('<<v[i].fi<<','<<v[i].se<<')';cout<<'\n';}
template<class T> void outvvp(T v){rep(i,v.size())outvp(v[i]);}
template<class T> void outv(T v){rep(i,v.size()){if(i)cout<<' ';cout<<v[i];}cout<<'\n';}
template<class T> void outvv(T v){rep(i,v.size())outv(v[i]);}
template<class T> void yesno(T b){if(b)out("yes");else out("no");}
template<class T> void YesNo(T b){if(b)out("Yes");else out("No");}
template<class T> void YESNO(T b){if(b)out("YES");else out("NO");}
template<class T> void outset(T s){auto itr=s.begin();while(itr!=s.end()){if(itr!=s.begin())cout<<' ';cout<<*itr;itr++;}cout<<'\n';}
void outs(ll a,ll b){if(a>=inf-10)out(b);else out(a);}
vp res;
void f(ll a,ll d){
    while(d>0){
        ll t=2;
        if(d==3)t=3;
        res.pb(a,t);
        d-=t;
    }
}
vp f1(ll n,vi v){
    res=vp(0);
    ll mid=n/2,pre=0;
    rep(i,mid)pre+=v[i];
    rep(i,mid+1){
        if(i==0)f(pre+1,v[mid]);
        else{
            pre-=v[mid-i];
            f(pre+1,v[mid-i]+v[mid+i]);
        }
    }
    return res;
}
vp f2(ll n,vi v,ll a,ll b){
    if(a==0)return f1(n,v);
    res=vp(0);
    ll mid=n/2,pre=0;
    rep(i,mid+b)pre+=v[i];
    rep(i,a){
        if(i==0)f(pre+1,v[mid+b]);
        else{
            pre-=v[mid+b-i];
            f(pre+1,v[mid+b-i]+v[mid+b+i]);
        }
    }
    vi nv;
    rep(i,mid+b-a)nv.pb(v[i]);
    nv.pb(v[mid+b-a]+v[mid+b+a]);
    REP(i,mid+b+a+1,n)nv.pb(v[i]);
    vp ans1=res;
    vp ans2=f1(nv.size(),nv);
    for(auto x:ans2)ans1.pb(x);
    return ans1;
}
vp sol(ll n,string s){
    vi v={1};
    vp res;
    REP(i,1,n){
        if(s[i]!=s[i-1])v.pb(0);
        v.back()++;
    }
    n=v.size();
    if(n%2){
        ll mid=n/2;
        if(v[mid]>1)return f1(n,v);
        ll a=0,b=0;
        while(a<=n/2&&v[mid-a]==1)a++;
        while(b<=n/2&&v[mid+b]==1)b++;
        if(a+b>n/2)return res;
        return f2(n,v,a,b);
    }
    else{
        vi idx;
        rep(i,n)if(v[i]>1)idx.pb(i);
        ll A=-1,B=0,C=-1,D=0;
        for(ll i=1;i<n;i+=2){
            while(A+1<idx.size()&&idx[A+1]<=i/2)A++;
            while(B<idx.size()&&idx[B]<i/2)B++;
            while(C+1<idx.size()&&idx[C+1]<=(n+i)/2)C++;
            while(D<idx.size()&&idx[D]<(n+i)/2)D++;
            if(A==-1||D==idx.size())continue;
            ll a=i/2-idx[A],b=idx[B]-i/2,c=(n+i)/2-idx[C],d=idx[D]-(n+i)/2;
            if(a+b<=i/2&&c+d<=(n-i)/2){
                vi v1,v2;
                rep(j,i)v1.pb(v[j]);
                REP(j,i,n)v2.pb(v[j]);
                vp res1=f2(i,v1,a,b),res2=f2(n-i,v2,c,d);
                for(auto x:res2)res1.pb(x);
                return res1;
            }
        }
        return res;
    }
}
void check(string s,vp ans){
    if(ans.size()==0)return;
    else{
        for(auto x:ans){
            ll a=x.fi-1,d=x.se;
            REP(i,a,a+d)assert(i<s.size()&&s[i]==s[a]);
            assert(d==2||d==3);
            string ns;
            rep(i,s.size())if(i<a||i>=a+d)ns+=s[i];
            s=ns;
        }
        assert(s=="");
    }
}
int main(){
    cin.tie(0);ios::sync_with_stdio(false);
    ll n;cin>>n;
    string s;cin>>s;
    vp ans=sol(n,s);
    // check(s,ans);
    if(ans.size())out(ans.size());
    else out(-1);
    for(auto x:ans)cout<<x.fi<<' '<<x.se<<'\n';
}