#include<stdio.h>
#include<string.h>
int main(void){
    char S[1000010];scanf("%s",S);
    int ls = strlen(S);
    int i;
    int v[3];
    for (i=0;i<ls;i++){
        if (S[i] == 't')v[0]++;
        if (S[i] == 'r')v[1]++;
        if (S[i] == 'e')v[2]++;
    }
    v[2] /= 2;
    
    int ans = 10000000;
    for (i=0;i<3;i++){
        if (v[i] < ans)ans = v[i];
    }
    printf("%d\n",ans);
    return 0;
}