#include<stdio.h>
#include<string.h>
int main(void){
	int d,i,b=25000;
	int a[3] = {};
	
	char c[1000000];
	scanf("%s",c);
	d = strlen(c);
	for(i=0;i<d;i++){
		if(c[i] == 'e') a[2]++;
		else if(c[i] == 't') a[0]++;
		else if(c[i] == 'r') a[1]++;
	}
	a[2] /=2;
	for(i=0;i<3;i++){
		if(b>a[i]) b=a[i];
	}
	printf("%d\n",b);
	return 0;
}