#include<bits/stdc++.h> //#pragma GCC target("avx2") //#pragma GCC optimize("O3") //#pragma GCC optimize("unroll-loops") using namespace std; using ll=long long; using ld=long double; using ull=unsigned long long; using i128 = __int128_t; #define rep(i,n) for(ll i=0;i<ll(n);i++) #define rep2(i,n) for(ll i=n-1;i>=0;i--) #define rep3(i,a,b) for(ll i=a;i<=ll(b);i++) #define rep4(i,a,b) for(ll i=a;i>=ll(b);i--) #define forv(i,V) for(const auto& i:V) #define all(x) x.begin(),x.end() #define fi first #define se second #define SIZE(x) int(x.size()) //constexpr ll mod=998244353; //constexpr ll mod=1000000007; #define pi 3.14159265358979323 #define INF32 2147483647 #define INF64 9223372036854775807 #define faster ios::sync_with_stdio(false);std::cin.tie(nullptr) #define pii pair<int, int> #define pll pair<ll, ll> #define pb push_back #define eb emplace_back #define mp make_pair #define rev reverse #define vi vector<int> #define vll vector<ll> #define vpi vector<pair<int,int>> #define vpll vector<pair<ll,ll>> #define vvi vector<vector<int>> #define vvll vector<vector<ll>> #define prq priority_queue #define lb lower_bound #define ub upper_bound const string YESNO[2] = {"NO", "YES"}; const string YesNo[2] = {"No", "Yes"}; const string yesno[2] = {"no", "yes"}; #define rall(n) (n).rbegin(),(n).rend() #define INT(...) int __VA_ARGS__;scan(__VA_ARGS__) #define LL(...) ll __VA_ARGS__;scan(__VA_ARGS__) #define STR(...) string __VA_ARGS__;scan(__VA_ARGS__) #define CHR(...) char __VA_ARGS__;scan(__VA_ARGS__) #define DBL(...) double __VA_ARGS__;scan(__VA_ARGS__) #define LD(...) ld __VA_ARGS__;scan(__VA_ARGS__) template<typename T,typename U> ostream &operator<<(ostream&os,const pair<T,U>&p){os<<p.first<<" "<<p.second;return os;} template<typename T,typename U> istream &operator>>(istream&is,pair<T,U>&p){is>>p.first>>p.second;return is;} template<typename T> ostream &operator<<(ostream&os,const vector<T>&v){for(auto it=v.begin();it!=v.end();){os<<*it<<((++it)!=v.end()?" ":"");}return os;} template<typename T> istream &operator>>(istream&is,vector<T>&v){for(T &in:v){is>>in;}return is;} void scan(){} template<class Head,class... Tail> void scan(Head&head,Tail&... tail){cin>>head;scan(tail...);} template<class T> void print(const T &t){cout<<t<<'\n';} template<class Head, class... Tail> void print(const Head &head, const Tail &... tail){cout<<head<<' ';print(tail...);} template<class... T> void fin(const T &... a){print(a...);exit(0);} ll max(int a,ll b){return max((ll)a,b);} ll max(ll a,int b){return max((ll)b,a);} ll min(int a,ll b){return min((ll)a,b);} ll min(ll a,int b){return min((ll)b,a);} //a以上b以下の個数 template<typename T> ll RangeOK(ll a,ll b,vector<T> &v){ return max(ub(all(v),b)-lb(all(v),a),0); } //setprecision(20) int main(){ LL(n); STR(s); ll now=0; ll ans=0; rep4(i,n-1,0){ if(s[i]=='#'){ ans=max(ans,now+n-i); now++; } else{ now--; now=max(now,0); } } fin(ans); }