#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <set>
#include <string>
#include <vector>
#define rep(i, n) for (int i = 0; i < n; ++i)
#define FOR(i, a, b) for (int i = a; i < b; ++i)
#define ll long long
#define pb(x) push_back(x)
using namespace std;

int main() {
  char c[14];
  rep(i, 14) cin >> c[i];
  int maxv = 0, cnt = 0;
  rep(i, 14) {
    if (c[i] == 'x') {
      cnt = 0;
    } else {
      cnt++;
      maxv = max(maxv, cnt);
    }
  }
  cout << maxv << endl;
  return 0;
}