#!/usr/bin/env python3

import sys

def solve(r, c, s):
  n = len(s)
  i = 0
  while i < n and s[i] == 'D': i += 1

  j = 0
  segs = []
  while i < n:
    j = i
    while j < n and s[j] == s[i]: j += 1
    segs.append(j - i)
    i = j
  if len(segs) % 2 == 1: segs.pop()

  p = len(segs) // 2
  ws, hs = [], []
  for i in range(p):
    ws.append(segs[2 * i])
    hs.append(segs[2 * i + 1])
  for i in range(1,p):
    ws[i] += ws[i - 1]
  for i in range(p-2,-1,-1):
    hs[i] += hs[i + 1]

  ans = min(hs[0], ws[-1]) if len(hs) > 0 else 0
  for i in range(p-1):
    ans = min(ans, ws[i] + hs[i + 1])

  return ans

r, c = map(int, sys.stdin.readline().split(' '))
s = sys.stdin.readline().rstrip()

print(solve(r, c, s) + solve(c, r, ''.join(['R' if ch == 'D' else 'D' for ch in s])))