#include <bits/stdc++.h>
using namespace std;

int INF = 1e8;

int main() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);

    int N; string S;
    cin >> N >> S;

    vector<int> left(N, INF);
    int prev = -INF;
    for (int i = 0; i < N; i++) {
        if (S[i] == '#') prev = i;
        left[i] = i - prev;
    }

    vector<int> right(N, INF);
    prev = INF;
    for (int i = N - 1; i >= 0; i--) {
        if (S[i] == '#') prev = i;
        right[i] = prev - i;
    }

    int answer = -INF;
    int max_dist = 0;

    for (int i = 0; i < N; i++) {
        int dist = min(left[i], right[i]);
        if (dist > max_dist) {
            answer = i + 1;
            max_dist = dist;
        }
    }

    cout << answer << '\n';
}