private class A {
    fun solve() {
        val s = nextToken()
        var ans = 0
        var cur = 0
        for (c in s) {
            if (c == 'R') cur++
            else cur = 0
            ans = Math.max(ans, cur)
        }
        println(ans)
    }

    var tokenBuffer = listOf<String>()
    var bufferPosition = 0

    private fun checkBuffer() {
        if (bufferPosition == tokenBuffer.size) {
            tokenBuffer = nextLine().split(" ")
            bufferPosition = 0
        }
    }

    fun nextLine() = readLine()!!
    fun nextInt(): Int {
        checkBuffer()
        return tokenBuffer[bufferPosition++].toInt()
    }

    fun nextLong(): Long {
        checkBuffer()
        return tokenBuffer[bufferPosition++].toLong()
    }

    fun nextDouble(): Double {
        checkBuffer()
        return tokenBuffer[bufferPosition++].toDouble()
    }

    fun nextToken(): String {
        checkBuffer()
        return tokenBuffer[bufferPosition++]
    }
}

fun main() {
    val reader = A().solve()

}
