#include <iostream>
#include <cstring>
using namespace std;

int min(int n, int m)
{
if(n<m) return n;
else return m;
}

int main()
{
char s[1000006];

cin >> s;

int t = 0;
int r = 0;
int e = 0;

for(int i=0; i<strlen(s); i++)
{
switch(s[i]) {
case 't' : t++;break;
case 'r' : r++;break;
case 'e' : e++;break;
}
}

cout << min(t, min(r, e/2)) << endl;

return 0;
}