import sequtils
# import algorithm,math,tables
# import times,macros,queues,bitops,strutils,intsets,sets
# import rationals,critbits,ropes,nre,pegs,complex,stats,heapqueue,sugar
template times*(n:int,body) = (for _ in 0..<n: body)
template `max=`*(x,y) = x = max(x,y)
template `min=`*(x,y) = x = min(x,y)
# template stopwatch(body) = (let t1 = cpuTime();body;stderr.writeLine "TIME:",(cpuTime() - t1) * 1000,"ms")
# proc `^`(n:int) : int{.inline.} = (1 shl n)
proc getchar_unlocked():char {. importc:"getchar_unlocked",header: "<stdio.h>" ,discardable.}
proc scan(): int =
  while true:
    let k = getchar_unlocked()
    if k < '0': return
    result = 10 * result + k.ord - '0'.ord

let n = scan()
let S = stdin.readLine()
var ans = 0
for d in 1..n:
  for i in 0..<n:
    if S[i] != 'U' : continue
    if i+d >= n or S[i+d] != 'M':continue
    if i+d+d >= n or S[i+d+d] != 'G' : continue
    ans += 1
echo ans