#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
using ll = long long;
int main()
{
string s;
cin >> s;
ll numt =0;
ll numr = 0;
ll nume = 0;
for(const char c : s){
if(c == 't'){
numt++;
} else if (c == 'r'){
numr++;
} else if (c == 'e'){
nume++;
}
}
cout << min(numt,min(numr, nume/2)) << endl;

return 0;
}