open System
type Sol() =
    member this.Solve() = 
        let S = stdin.ReadLine()
        
        let rec cCnt ss ret c = 
            match ss with
            | [] -> ret
            | x :: tail -> cCnt tail (ret + (if x = c then 1 else 0 )) c
        
        let ts = cCnt (Seq.toList S) 0 't'
        let rs = cCnt (Seq.toList S) 0 'r' 
        let es = ( cCnt (Seq.toList S) 0 'e' ) / 2
        
        printfn "%d" (Seq.min (ts::rs::es::[]) )
        
let mySol = new Sol()
mySol.Solve()