#include <bits/stdc++.h>
typedef unsigned long long ul;
typedef signed long long ll;

int main(void)
{
  std::cin.tie(0);
  std::ios::sync_with_stdio(false);
  std::cout << std::fixed;
  std::string s;
  std::cin >> s;
  int ans = 0;
  for (auto c : s) {
    if (c == 'n') ans++;
  }
  std::cout << ans << std::endl;
  return 0;
}