#include <stdio.h>

int main(void) {
    char S[101];
    int i, C = 0,C1=0,C2=0;
    
    scanf("%s", S);
    for (i = 0; S[i] != 0; i++) {
    	if (S[i] == 't') {
    		C++;
    	}
    	else if (S[i] == 'r') {
    		C1++;
    	}
    	else if (S[i] == 'e') {
    		C2++;
    	}
    }
    if (C + C1 == C2) {
    	printf("%d", C);
    }
    else {
    	printf("0");
    }
}