func main()
	var N: int :: cui@input().toInt(&)
	var S: []char :: cui@input()
	var ans: int
	for i(0, N - 3)
		if(S[i] <> 'U')
			skip i
		end if
		for j(i + 1, N - 2)
			if(S[j] <> 'M')
				skip j
			end if
			if(2 * j - i < N & S[2 * j - i] = 'G')
				do ans :+ 1
			end if
		end for
	end for
	do cui@print("\{ans}\n")
end func