import java.io.BufferedReader
import java.util.*

fun main() = abc175a()

@OptIn(ExperimentalStdlibApi::class)
fun abc175a() = SimpleFastIOWithToken_abc175a().exec {
    val s = readString()

    val answer = when {
        s.contains("RRR") -> 3
        s.contains("RR") -> 2
        s.contains("R") -> 1
        else -> 0
    }

    println(answer)
}

// region kokokara template dayo (^o^)
@Suppress("unused", "HasPlatformType", "MemberVisibilityCanBePrivate", "ClassName")
private class SimpleFastIOWithToken_abc175a(private val separator: String = System.lineSeparator()) {
    private val br: BufferedReader = System.`in`.bufferedReader()
    private var st: StringTokenizer = StringTokenizer("")
    private val sb: StringBuilder = StringBuilder()
    private fun prepareNext() = run { if (!st.hasMoreTokens()) st = StringTokenizer(br.readLine()) }

    fun readString(): String = run { prepareNext() }.run { st.nextToken() }
    fun readInt(): Int = Integer.valueOf(readString())
    fun readLong(): Long = java.lang.Long.valueOf(readString())

    fun println(): Unit = run { sb.append(separator) }
    fun print(any: Any): Unit = run { sb.append(any) }
    fun println(any: Any): Unit = run { sb.append(any.toString() + separator) }

    fun exec(action: SimpleFastIOWithToken_abc175a.() -> Unit) {
        var t: Throwable? = null
        Thread(null, { action() }, "solve", 128 * 1024 * 1024)
            .apply { setUncaughtExceptionHandler { _, t1 -> t = t1 } }
            .apply { start() }.join()
        t?.let { throw it }
        kotlin.io.print(sb)
    }

    fun readLine(): Nothing = error("readLine is disabled.")
}
// endregion kokomade template dayo (^o^)
