#include    <stdio.h>

int main(void)
{
    char    c;
    int     t, r, e, n;

    n = t = r = e = 0;
    while ((c = getchar()) != EOF) {
        if (c == '\n') {
            break;
        }
        switch (c) {
          case 't':
            t++;
            break;
          case 'r':
            r++;
            break;
          case 'e':
            e++;
            break;
          default:
            break;
        }
        if ((t > 0) && (r > 0) && (e > 1)) {
            t--;
            r--;
            e -= 2;
            n++;
        }
    }

    printf("%d\n", n);

    return 0;
}