#include<bits/stdc++.h>
#include<atcoder/all>
#define ep emplace
#define eb emplace_back
#define all(a) begin(a),end(a)
#define wh(...) while(__VA_ARGS__)
#define ef(...) else if(__VA_ARGS__)
#define done(...) rr pp(__VA_ARGS__)
#define LL(...) RD(ll,__VA_ARGS__)
#define ST(...) RD(str,__VA_ARGS__)
#define RD(T,...) T __VA_ARGS__;li(__VA_ARGS__)
#define UL(n,...) u1 __VA_ARGS__;resize({n},__VA_ARGS__);li(__VA_ARGS__)
#define UV(n,...) u1 __VA_ARGS__;resize({n},__VA_ARGS__);vi(__VA_ARGS__)
#define SS(n,...) strs __VA_ARGS__;resize({n},__VA_ARGS__);li(__VA_ARGS__)
#define U2(n,m,...) u2 __VA_ARGS__;resize({n,m},__VA_ARGS__);li(__VA_ARGS__)
#define fe(v,e,...) for(au&&__VA_OPT__([)e __VA_OPT__(,__VA_ARGS__)__VA_OPT__(]):v)
#define fo(i,...) for(au[i,i##stop,i##step]=rng_fo(0,__VA_ARGS__);i<i##stop;i+=i##step)
#define of(i,...) for(au[i##stop,i,i##step]=rng_fo(1,__VA_ARGS__);i>=i##stop;i-=i##step)
#define debug(...) pp(#__VA_ARGS__,__VA_ARGS__)
#define I(...) template<__VA_ARGS__>
#define J typename
#define O operator
#define au auto
#define cs const
#define ifc if constexpr
#define rr return
#define uu using
namespace my{uu vo=void;vo main();vo solve();}int main(){my::main();}namespace my{uu namespace std;uu is=istream;uu os=ostream;
uu bo=bool;uu dd=long double;uu ll=long long;uu ull=unsigned long long;uu lll=__int128_t;uu ulll=__uint128_t;
I(J T)uu ilis=initializer_list<T>;I(J T)uu v1=vector<T>;I(J T)uu v2=v1<v1<T>>;uu u1=v1<ll>;uu u2=v2<ll>;uu str=string;uu strs=v1<str>;
uu namespace atcoder;uu ml=modint998244353;is&O>>(is&i,ml&x){ll t;i>>t;x=t;rr i;}os&O<<(os&o,cs ml&x){rr o<<x.val();}uu m1=v1<ml>;
I(J A,J B=A)struct cp{A a={};B b={};cp(){}cp(A a,B b):a(a),b(b){}cp(pair<A,B>p):a(p.first),b(p.second){}cp O-()cs{rr cp(-a,-b);}
  cp&O+=(cs cp&c){a+=c.a,b+=c.b;rr*this;}cp O+(cs cp&c)cs{rr cp{*this}+=c;}bo O==(cs cp&c)cs{rr a==c.a&&b==c.b;}
  cp&O-=(cs cp&c){a-=c.a,b-=c.b;rr*this;}cp O-(cs cp&c)cs{rr cp{*this}-=c;}auto O<=>(cs cp&c)cs{rr a!=c.a?a<=>c.a:b<=>c.b;}
};uu cl=cp<ll>;uu cls=v1<cl>;I(J T)uu qmax=priority_queue<T>;I(J T)uu qmin=priority_queue<T,v1<T>,greater<>>;bo add(au&a,cs au&b){rr a+=b;}
I(J T)struct set:std::set<T>{set(v1<T>a={}){fe(a,e)this->ep(e);}};I(J T)struct uset:unordered_set<T>{uset(v1<T>a={}){fe(a,e)this->ep(e);}};
I(J T)struct mset:multiset<T>{mset(v1<T>a={}){fe(a,e)this->ep(e);}vo erase(cs T&x){if(this->contains(x))multiset<T>::erase(this->find(x));}};
I(J T,J U=T)uu map=std::map<T,U>;I(J T,J U=T)uu umap=unordered_map<T,U>;str Yes(bo y=1){rr y?"Yes":"No";}str No(){rr Yes(0);}
ll oo=3e18;dd ee=1e-12;u1 dx{-1,0,1,0,-1,1,1,-1},dy{0,-1,0,1,-1,-1,1,1};str sp=" ",nc="",nl="\n";ll len(cs au&a){rr a.size();}
ll rnd(ll l,ll r=oo){static ull x=76,y=53,z=20,w=41;ull t=x^(x<<11);x=y,y=z,z=w,w=(w^(w>>19))^(t^(t>>8));if(r==oo)r=l,l=0;rr w%(r-l)+l;}
ll l2(ulll x){x|=1;ll r=0;wh(x)x>>=1,++r;rr r;}bo odd(ll x){rr x&1;}ll pwm1(ll x){rr 1-2*(x&1);}bo at(au x,ll i){rr x>>i&1;}
ll l10(ulll x){x|=1;ll r=0;wh(x)x/=10,++r;rr r;}bo eve(ll x){rr~x&1;}ll pw2(ll n){rr 1LL<<n;}bo in(au l,au x,au r){rr l<=x&&x<r;}
au flo(au x,au y){rr y<0?x=-x,y=-y:x>=0?x/y:(x+1)/y-1;}au rng_fo(bo s,ll a,ll b=oo,ll c=1){if(b==oo)b=a,a=0;rr tuple{a,b-s,c};}
au cei(au x,au y){rr y<0?x=-x,y=-y:x<=0?x/y:(x-1)/y+1;}au zz(au x){rr x<0?-x:x;}au sq(au a){rr a*a;}au cb(au a){rr a*a*a;}

I(J T)au&O+=(v1<T>&v,cs v1<T>&u){fo(i,len(v))v[i]+=u[i];rr v;}I(J T)au O+(v1<T>v,cs v1<T>&u){rr v+=u;}I(J T)constexpr bo isv=0;
I(J T)au&O-=(v1<T>&v,cs v1<T>&u){fo(i,len(v))v[i]-=u[i];rr v;}I(J T)au O-(v1<T>v,cs v1<T>&u){rr v-=u;}I(J T)constexpr bo isv<v1<T>> =1;
I(J T)au&O+=(v1<T>&v,cs au&x){fe(v,e)e+=x;rr v;}I(J T)au O+(v1<T>v,cs au&x){rr v+=x;}I(J T)au&O++(v1<T>&v){rr v+=1;}
I(J T)au&O-=(v1<T>&v,cs au&x){fe(v,e)e-=x;rr v;}I(J T)au O-(v1<T>v,cs au&x){rr v-=x;}I(J T)au&O--(v1<T>&v){rr v-=1;}
I(J T)au&O^=(v1<T>&v,cs v1<T>&u){fe(u,e)v.eb(e);rr v;}I(J T)au O^(v1<T>v,cs v1<T>&u){rr v^=u;}I(J T)vo af(v1<T>&a,T e={}){a.ep(begin(a),e);}
I(J F=less<>)au&srt(au&a,F f={}){sort(all(a),cref(f));rr a;}au&rv(au&a){reverse(all(a));rr a;}vo df(au&a){a.erase(begin(a));}
au&rsr(au&a){rr rv(srt(a));}au&uq(au&a){srt(a).erase(unique(all(a)),end(a));rr a;}u1 io(ll n,ll x=0){u1 a;fo(i,n)a.eb(i+x);rr a;}
decltype(au)bg(au&a){rr*begin(a);}I(J T)T pof(deque<T>&q){T r=bg(q);q.pop_front();rr r;}bo amax(au&a,cs au&b){rr a<b?a=b,1:0;}
decltype(au)rb(au&a){rr*rbegin(a);}I(J T)T pob(deque<T>&q){T r=rb(q);q.pop_back();rr r;}bo amin(au&a,cs au&b){rr a>b?a=b,1:0;}
decltype(au)rb(au&a,ll x){rr*(rbegin(a)+x);}I(J T)au pop(T&a){ifc(isv<T>){au r=rb(a);a.pop_back();rr r;}else{au r=a.top();a.pop();rr r;}}
I(J...A)au max(cs A&...a){rr max(ilis<common_type_t<A...>>{a...});}I(J T)ll arglb(cs v1<T>&v,cs au&x){rr lower_bound(all(v),x)-begin(v);}
I(J...A)au min(cs A&...a){rr min(ilis<common_type_t<A...>>{a...});}I(J T)ll argub(cs v1<T>&v,cs au&x){rr upper_bound(all(v),x)-begin(v);}
I(J T=ll,ll n,ll i=0)au vec(cs ll(&l)[n],T x={}){ifc(n==i+1)rr v1<T>(l[i],x);else rr vector(l[i],vec<T,n,i+1>(l,x));}
I(J S,bo f(S&,cs S&),J V)au scan(cs V&v){cp<S,bo>r;ifc(!isv<V>)r={v,1};else fe(v,x)if(au t=scan<S,f>(x);t.b)!r.b?r=t,0:f(r.a,t.a);rr r;}
I(J V)au pv(V){ifc(isv<V>)rr pv(V(1)[0]);else rr V();}I(J V)uu pt=decltype(pv(V()));I(J V)au sum(cs v1<V>&v){rr scan<pt<V>,add>(v).a;}
I(J V)au zt(V v){ifc(isv<V>){fe(v,e)e=zt(e);fo(i,len(v)-1)v[i+1]+=v[i];}rr v;}I(J V)au max(cs v1<V>&v){rr scan<pt<V>,amax>(v).a;}
I(J V)au mb(V v){ifc(isv<V>){fe(v,e)e=mb(e);of(i,len(v)-1)v[i+1]-=v[i];}rr v;}I(J V)au min(cs v1<V>&v){rr scan<pt<V>,amin>(v).a;}
I(J V)vo fill(v1<V>&v,pt<V>x={}){fe(v,e)ifc(isv<V>)fill(e,x);else e=x;}I(ll n)vo resize(cs ll(&l)[n],au&...a){((a=vec(l,pv(a))),...);}

struct fio{fio(){cin.tie(0)->sync_with_stdio(0);cout<<fixed<<setprecision(12);}}fio;
os&O<<(os&o,cs ulll&x){rr(x<10?o:o<<x/10)<<ll(x%10);}os&O<<(os&o,cs lll&x){rr o<<(x<0?"-":nc)<<ulll(zz(x));}
I(J V)os&O<<(os&o,cs v1<V>&v){str s=nl;ifc(!isv<V>)s=sp;else ifc(isv<J V::value_type>)s+=nl;fe(v,e)o<<e<<(&e==&rb(v)?nc:s);rr o;}
I(J T)os&O<<(os&o,cs deque<T>&v){fe(v,e)o<<e<<sp;rr o;}I(J T,J U)os&O<<(os&o,cs cp<T,U>&c){rr o<<c.a<<sp<<c.b;}
I(J T)os&O<<(os&o,cs set<T>&v){fe(v,e)o<<e<<sp;rr o;}I(J T,J U)os&O<<(os&o,cs map<T,U>&m){fe(m,e)o<<cp(e)<<nl;rr o;}
I(J T)os&O<<(os&o,cs mset<T>&v){fe(v,e)o<<e<<sp;rr o;}vo pp(cs au&...a){ll i=0;((cout<<a<<(++i==sizeof...(a)?nc:sp)),...);cout<<nl;}
I(J T)is&O>>(is&i,v1<T>&v){fe(v,e)i>>e;rr i;}vo li(au&...a){(cin>>...>>a);}vo vi(au&...a){fo(i,(len(a)&...))(cin>>...>>a[i]);}

struct edg{ll t,w;edg(){}edg(ll t,ll w=1):t(t),w(w){}};uu graph=v2<edg>;
graph tog(cs u2&a){graph g;fe(a,e){g.eb();fe(e,v)rb(g).eb(v);}rr g;}u2 tou(cs graph&g){u2 a;fe(g,e){a.eb();fe(e,v,w)rb(a).eb(v);}rr a;}
I(J G)au ygi(G&g,ll m,bo f=1){ifc(is_same_v<G,u2>){UV(m,a,b);a-=f,b-=f;fo(i,m)g[a[i]].eb(b[i]);rr tuple{a,b};}
  else{UV(m,a,b,c);a-=f,b-=f;fo(i,m)g[a[i]].eb(b[i],c[i]);rr tuple{a,b,c};}}
I(J G)au mgi(G&g,ll m,bo f=1){ifc(is_same_v<G,u2>){au[a,b]=ygi(g,m,f);fo(i,m)g[b[i]].eb(a[i]);rr tuple{a,b};}
  else{au[a,b,c]=ygi(g,m,f);fo(i,m)g[b[i]].eb(a[i],c[i]);rr tuple{a,b,c};}}I(J G)au ti(G&g,bo f=1){rr mgi(g,len(g)-1,f);}
u1 en(cs str&s,cs str&b="a"){u1 r;fe(s,e)r.eb(len(b)==1?e-b[0]:b.find_first_of(e));rr r;}u1 sien(cs str&b="a"){RD(str,s);rr en(s,b);}
u2 en(cs strs&s,cs str&b="a"){u2 r;fe(s,e)r.eb(en(e,b));rr r;}u2 sien(ll n,cs str&b="a"){strs s(n);li(s);rr en(s,b);}
str de(cs u1&a,cs str&b="a"){str r;fe(a,e)r+=len(b)==1?e+b[0]:0<=e&&e<len(b)?b[e]:'|';rr r;}
strs de(cs u2&a,cs str&b="a"){strs r;fe(a,e)r.eb(de(e,b));rr r;}

I(J F)struct rec:F{rec(F&&f):F(forward<F>(f)){}I(J...A)decltype(au)O()(A&&...a)cs{rr F::O()(*this,std::forward<A>(a)...);}};
u1 zi(au&...a){u1 v=(a^...);uq(v);([&](u1&u){fe(u,e)e=arglb(v,e);}(a),...);rr v;}vo dec(au&...a){((--a),...);}
u1 vs(au f,au&...a){u1 o=io((len(a)&...));srt(o,cref(f));([&](au&e){au c=e;fo(i,len(e))e[i]=c[o[i]];}(a),...);rr o;}
dd bsd(au f,dd o,dd n){fo(t,l2(abs(o-n)/ee)+5)(f((o+n)/2)?o:n)=(o+n)/2;rr o;}ll sqr(ll x){ll r=sqrt(abs(x-ee));wh(r+1<=x/(r+1))++r;rr r;}
ll bsl(au f,ll o,ll n){wh(abs(o-n)>1)(f((o+n)/2)?o:n)=(o+n)/2;rr o;}u1 divs(ll n){u1 r;fo(i,1,sqr(n)+1)if(n%i==0)r.eb(i),r.eb(n/i);rr uq(r);}
cls fact(ll n){umap<ll>m;fo(i,2,sqr(n)+1)wh(n%i==0)++m[i],n/=i;if(n>1)++m[n];cls r;fe(m,e)r.eb(e);rr srt(r);}
cls rle(cs u1&a){cls r;fe(a,e)len(r)&&e==rb(r).a?++rb(r).b:r.eb(e,1).b;rr r;}cls rce(u1 a){rr rle(srt(a));}
lll pow(lll x,ulll n,ulll m=0){lll r=1;wh(n)n&1?r*=x:r,x*=x,m?r%=m,x%=m:r,n>>=1;rr r;}

vo main(){ll T=1;fo(t,T)solve();}
vo solve(){
  LL(N);
  u1 s=sien("con");
  
  u2 cnt(3,u1(3));
  fo(i,N*3){
    if(s[i]>=0)cnt[i%3][s[i]]++;
  }
  
  ll ans=0;
  ll su=0;
  fo(i,3){
    ll t=min(cnt[i][0],cnt[(i+1)%3][1],cnt[(i+2)%3][2]);
    amin(t,(N*3-su)/3);
    su+=t*3+1;
    ans+=t;
  }
  pp(ans);
}}