#include <bits/stdc++.h>
using namespace std;
const int MXN = 1000100;
const long long inf = 1e15;
const int mod = 1000000007;
char s[MXN];
int was[2 * MXN];
int main() {
  scanf("%s", s);
  int n = strlen(s);
  if (s[n - 1] == 'L') {
    for (int i = 0; i < (n); i++) {
      if (s[i] == 'R')
        s[i] = 'L';
      else
        s[i] = 'R';
    }
  }
  for (int i = 0; i < (n); i++) {
    if (s[i] == 'R')
      s[i] = 1;
    else
      s[i] = -1;
  }
  int cur = 0;
  int mn = 0, mx = 0, cmx = 0, tmx = 0;
  for (int i = 0; i < (n); i++) {
    was[cur + n] = 1;
    cur += s[i];
    tmx = max(tmx, cur);
    if (cur < mn) {
      mn = cur;
      mx = -1e9;
      cmx = 0;
    }
    if (cur > mx) {
      mx = cur;
      cmx = 1;
    } else if (cur == mx) {
      cmx++;
    }
  }
  if (!was[cur + n]) {
    printf("1\n");
    return 0;
  }
  if (cur == mx && cmx == 1) {
    if (cur - mn > tmx) {
      printf("%d\n", cur - mn - tmx);
      return 0;
    }
  }
  printf("0");
}
