import std.stdio,
       std.conv,
       std.string,
       std.range,
       std.math,
       std.bigint,
       std.algorithm;

void main()
{
    auto S = readln.strip;

    int[char] dict;
    S.each!(a => dict[a]++);
    (min(dict['t'] * 2, dict['r'] * 2, dict['e']) / 2).writeln;
}