#include <bits/stdc++.h>

using namespace std;

int main() {
    vector<int> vt;
    vt.push_back(-1);
    for (int i = 0; i < 14; ++i) {
        char c;
        cin >> c;
        if (c == 'x') vt.push_back(i);
    }
    vt.push_back(14);

    int ans = 0;
    for (int i = 0; i + 1 < vt.size(); ++i) {
        ans = max(ans, vt[i + 1] - vt[i] - 1);
    }
    cout << ans << endl;
    return 0;
}