import java.io.InputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Comparator;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.Map;
import java.util.PriorityQueue;
import java.math.BigDecimal;
import java.math.BigInteger;
    
public class Main{
 
static final InputStream in=System.in;
static final PrintWriter out=new PrintWriter(System.out);
static final int INF=Integer.MAX_VALUE;
static final long LINF=Long.MAX_VALUE/2;
 
public static void main(String[] args) throws IOException{
InputReader ir=new InputReader(in);
int t=0;
int r=0;
int e=0;
String s=ir.next();
for(int i=0;i<s.length();i++){
 char c=s.charAt(i);
 if(c=='t') t++;
 if(c=='r') r++;
 if(c=='e') e++;
}
out.println(Math.min(t,Math.min(r,(int)e/2)));
out.flush();
}

static class InputReader {
private InputStream in;
private byte[] buffer=new byte[1024];
private int curbuf;
private int lenbuf;
 
public InputReader(InputStream in) {this.in=in;}
  
public int readByte() {
if(lenbuf==-1) throw new InputMismatchException();
if(curbuf>=lenbuf){
curbuf= 0;
try{
lenbuf=in.read(buffer);
}
catch (IOException e) {
throw new InputMismatchException();
}
if(lenbuf<=0)
return -1;
}
return buffer[curbuf++];
}
 
public boolean isSpaceChar(int c){return !(c>=33&&c<=126);}
 
private int skip() {int b; while((b = readByte())!=-1&&isSpaceChar(b)); return b;}
 
public String next() {
int b=skip();
StringBuilder sb=new StringBuilder();
while(!isSpaceChar(b)){
sb.appendCodePoint(b);
b=readByte();
}
return sb.toString();
}
 
public int nextInt() {
int c=readByte();
while (isSpaceChar(c)) c=readByte();
boolean minus=false;
if (c=='-') {
minus=true;
c=readByte();
}
int res=0;
do{
if(c<'0'||c>'9') throw new InputMismatchException();
res=res*10+c-'0';
c=readByte();
}while(!isSpaceChar(c));
return (minus)?-res:res;
}
 
public long nextLong() {
int c=readByte();
while (isSpaceChar(c)) c=readByte();
boolean minus=false;
if (c=='-') {
minus=true;
c=readByte();
}
long res = 0;
do{
if(c<'0'||c>'9') throw new InputMismatchException();
res=res*10+c-'0';
c=readByte();
}while(!isSpaceChar(c));
return (minus)?-res:res;
}
 
public double nextDouble(){return Double.parseDouble(next());}
 
public BigInteger nextBigInteger(){return new BigInteger(next());}
 
public int[] nextIntArray(int n){
int[] a=new int[n];
for(int i=0;i<n;i++) a[i]=nextInt();
return a;
}
 
public char[][] nextCharMap(int n,int m){
char[][] map=new char[n][m];
for(int i=0;i<n;i++) map[i]=next().toCharArray();
return map;
}
}
}