let input = require('fs').readFileSync('/dev/stdin', 'utf8');

const COUNT = Array(3).fill(0);
[...input].forEach(v => {
  if(v == 't'){
    COUNT[0]++;
  }else if(v == 'r'){
    COUNT[1]++;
  }else if(v == 'e'){
    COUNT[2]++;
  }
});
let TMP = 0;
while (1) {
  COUNT[0]--;
  COUNT[1]--;
  COUNT[2] -= 2;
  if (!COUNT.every(v => v >= 0)) {
    console.log(TMP);
    return;
  }
  TMP++;
}