#include <iostream>
#include <algorithm>
#include <cmath>
#include <vector>
#include <string>
#include <cstring>
#include <cstdlib>
#include <iomanip>
#include <map>
#include <set>
#include <unordered_map>
#include <unordered_set>

using namespace std;


long long dp[2][200005];

signed main() {
	ios_base::sync_with_stdio(false);
	cin.tie(nullptr);
	cout.tie(nullptr);
	freopen("hike.in", "r", stdin);
	freopen("hike.out", "w", stdout);
	string s;
	cin >> s;
	dp[0][0] = 0;
	dp[1][0] = 1;
	for (int i = 0; i < s.length(); i++) {
		if (s[i] == 'L') {
			dp[0][i + 1] = min(dp[0][i] + 1, dp[1][i] + 1);
			dp[1][i + 1] = min(dp[0][i] + 2, dp[1][i]);
		}
		else if (s[i] == 'R') {
			dp[0][i + 1] = min(dp[0][i], dp[1][i] + 2);
			dp[1][i + 1] = min(dp[0][i] + 1, dp[1][i] + 1);
		}
		else {
			dp[0][i + 1] = min(dp[0][i] + 1, dp[1][i] + 2);
			dp[1][i + 1] = min(dp[0][i] + 2, dp[1][i] + 1);
		}
	}
	cout << dp[1][s.length()];
	return 0;
}