#include <bits/stdc++.h>
using namespace std;
//#include <atcoder/all>
//using namespace atcoder;
#define ll long long
#define GET_REP(_1, _2, _3, _4,NAME, ...) NAME
#define rep1(i, n) for (int i = 0; i < (n); ++i)
#define rep2(i, m, n) for (int i = (n); i < (m); ++i)
#define rep3(i, m, n, o) for (int i = (n); i < (m); i+=o)
#define rep(...) GET_REP(__VA_ARGS__, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep1(i,n) for (int i = (n); i > 0; i--)
#define nall(a) a.begin(),a.end()
#define rall(a) a.rbegin(),a.rend()
#define fi first
#define se second
#define getvec(a,n,s) \
    vector<s> a(n);\
    for (auto& i:a) cin >>i;
#define int long long
#define vi vector<int>
#define vpii vector<pair<int,int>>
#define vs vector<string>
#define vvi vector<vector<int>>
#define vvs vector<vector<string>>

template <typename T>
    auto vec(size_t n, T val) {
    return std::vector<T>(n, val);
}
template <typename... Sizes>
    auto vec(size_t n, Sizes... sizes) {
    return std::vector<decltype(vec(sizes...))>(n, vec(sizes...));
}
random_device rd;
mt19937 gen(rd());
//uniform_int_distribution<int> dist();

signed main() {
    int n;
    cin >> n;
    string s;
    cin >> s;
    vi a(n, 1000000);
    int now = 3141592;
    rep(i, n) {
        if(s[i] == '#') now = 0;
        a[i] = min(a[i], now);
        now++;
    }
    now = 199990;
    for(int i = n - 1; i >= 0; i--) {
        if(s[i] == '#') now = 0;
        a[i] = min(a[i], now);
        now++;
    }
    //rep(i, n) cout << a[i] << " ";
    //cout << endl;
    
    int ind = 0, nowm = 0;
    rep(i, n) {
        if(nowm < a[i]) {
            nowm = a[i];
            ind = i;
        }
    }
    cout << ind + 1 << endl;
}