#include <iostream>
using namespace std;

int ch[26];
int main(void) {
string s;cin>>s;
for (int i=0;i<s.length();++i) {
ch[s[i]-'a']++;
}
int mi = 1e7;
mi = min(mi, ch[19]);
mi = min(mi, ch[17]);
mi = min(mi, ch[4] / 2);
cout << mi << endl;
}