let n = stdin.ReadLine () |> int
let s = stdin.ReadLine ()


[|
    for i in 0..(n-1)/2 ->
        [|
            for j in 0..n-3-2*i ->
                s.[j] = 'U' && s.[j+i+1] = 'M' && s.[j+2*i+2] = 'G'
        |]
|] |> Array.concat |> Array.filter id |> Array.length |> printfn "%d"