import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.Scanner;

public class Main {

	static int ans;

	public static void main(String[] args) {

		Scanner sc = new Scanner(System.in);
		String s = sc.next();
		int count = 0;
		int max = 0;
		boolean t = false;
		for(int i = 0; i < s.length();i++) {
			if(t && s.charAt(i) == 'R') {
				count++;
			}
			else if(s.charAt(i) == 'R') {
				count=1;
				t = true;
			}
			else {
				count = 0;
				t = false;
			}
			if(count > max) {
				max = count;
			}
		}
		System.out.println(max);
	}

	//return gcd O(logN)
	public static int gcd(int num1,int num2) {
		if(num2==0) return num1;
		else return gcd(num2,num1%num2);
	}

	//return nCk mod M (M must be prime number) O(min(k,n-k)*logM)
	public static int nCk(int n,int k,int M) {
		long ret = 1;
		int min = Math.min(k, n-k);
		for(int i=1;i<=min;i++) {
			ret = (ret * pow(i,M-2,M)) % M;
		}
		for(int i=n-min+1;i<=n;i++) {
			ret = (ret * i) % M;
		}
		return (int)ret;
	}

	//return a^b mod M O(logB)
	public static long pow(long a,long b,int M) {
		long ret = 1;
		long tmp = a;
		while(b>0) {
			if((b&1)==1) ret = (ret * tmp) % M;
			tmp = (tmp * tmp) % M;
			b = b>>1;
		}
		return ret;
	}

	//return root node idx O(a(N)) ( O(1)<O(a(N))<O(logN) )
	public static int find(int[] tree,int idx) {
		if(tree[idx]==idx) return idx;
		else return tree[idx] = find(tree,tree[idx]);
	}

	//union idx2 tree to idx1 tree O(a(N))
	public static void union(int[] tree,int idx1,int idx2) {
		int root1 = find(tree,idx1);
		int root2 = find(tree,idx2);
		tree[root2] = root1;
	}

	//add value at idx on bit O(logN)
	public static void add(int[] bit,int idx,int value) {
		for(int i=idx;i<bit.length;i+=(i&-i)) bit[i] += value;
	}

	//return sum [1,idx] O(logN)
	public static int sum(int[] bit,int idx) {
		int ret = 0;
		for(int i=idx;i>0;i-=(i&-i)) ret += bit[i];
		return ret;
	}

	//return min distance from start to end O(ElogV) (negative cost is prohibited)
	//edge is int[3] array {from,to,cost}
	//edges is edge list from specific node
	//all_edges is Map<from node number,edges>
	public static int dijkstra(Map<Integer,List<int[]>> all_edges,int start,int end,int max_node_number) {
		int[] distance = new int[max_node_number+1];
		for(int i=0;i<distance.length;i++) distance[i] = -1;
		PriorityQueue<int[]> p_que = new PriorityQueue<>((a,b)->((distance[a[0]]+a[2])-(distance[b[0]]+b[2])));
		distance[start] = 0;
		List<int[]> edges = all_edges.get(start);
		for(int i=0;i<edges.size();i++) p_que.add(edges.get(i));
		while(distance[end]<0) {
			int[] nearest_edge = p_que.poll();
			if(distance[nearest_edge[1]]<0) {
				distance[nearest_edge[1]] = distance[nearest_edge[0]] + nearest_edge[2];
				if(all_edges.containsKey(nearest_edge[1])) {
					edges = all_edges.get(nearest_edge[1]);
					for(int i=0;i<edges.size();i++) {
						int[] edge = edges.get(i);
						if(distance[edge[1]]<0) p_que.add(edge);
					}
				}
			}
		}
		return distance[end];
	}

	//return min distance from start to end O(EV) (negative cost is possible)
	//edge is int[3] array {from,to,cost}
	//edges is edge list from specific node
	//all_edges is Map<from node number,edges>
	public static int bellmanFord(Map<Integer,List<int[]>> all_edges,int start,int end,int max_node_number) {
		int[] distance = new int[max_node_number+1];
		int INF = Integer.MAX_VALUE;
		for(int i=0;i<distance.length;i++) {
			distance[i] = INF;
		}
		distance[start] = 0;
		int counter = all_edges.size();
		while(counter>0) {
			boolean updated = false;
			for(List<int[]> edges: all_edges.values()) {
				if(distance[edges.get(0)[0]]==INF) continue;
				for(int[] edge: edges) {
					if(distance[edge[0]]+edge[2] < distance[edge[1]]) {
						distance[edge[1]] = distance[edge[0]]+edge[2];
						updated = true;
					}
				}
			}
			if(!updated) break;
			counter--;
		}
		return counter==0?Integer.MIN_VALUE:distance[end];
	}

	//return new distance matrix O(logV^3)
	public static int[][] warshallFloyd(int[][] distance){
		int node_number = distance.length;
		int[][] min_distance = new int[node_number][node_number];
		for(int i=0;i<node_number;i++) {
			for(int j=0;j<node_number;j++) {
				min_distance[i][j] = distance[i][j];
			}
		}
		for(int via=0;via<node_number;via++) {
			for(int from=0;from<node_number;from++) {
				for(int to=0;to<node_number;to++) {
					min_distance[from][to] = Math.min(min_distance[from][to], min_distance[from][via]+min_distance[via][to]);
				}
			}
		}
		return min_distance;
	}


	//return min cost for union all nodes O(ElogV)
	//edge is int[3] array {node1,node2,cost}
	//edges is edge list
	public static int kruskal(List<int[]> edges,int max_node_number) {
		edges.sort((a,b)->(a[2]-b[2]));
		int[] uft = new int[max_node_number+1];
		for(int i=0;i<uft.length;i++) {
			uft[i] = i;
		}
		int cost_sum = 0;
		for(int[] edge: edges) {
			if(find_krusk(uft,edge[0])!=find_krusk(uft,edge[1])) {
				union_krusk(uft,edge[0],edge[1]);
				cost_sum += edge[2];
			}
		}
		return cost_sum;
	}

	public static int find_krusk(int[] tree,int idx) {
		if(tree[idx]==idx) return idx;
		else return tree[idx] = find(tree,tree[idx]);
	}

	public static void union_krusk(int[] tree,int idx1,int idx2) {
		int root1 = find(tree,idx1);
		int root2 = find(tree,idx2);
		tree[root2] = root1;
	}
}

Measured memory_bytes: 35636