// dfmt off
T lread(T=long)(){return readln.chomp.to!T;}T[] lreads(T=long)(long n){return iota(n).map!((_)=>lread!T).array;}
T[] aryread(T=long)(){return readln.split.to!(T[]);}void arywrite(T)(T a){a.map!text.join(' ').writeln;}
void scan(L...)(ref L A){auto l=readln.split;foreach(i,T;L){A[i]=l[i].to!T;}}alias sread=()=>readln.chomp();
void dprint(L...)(lazy L A){debug{auto l=new string[](L.length);static foreach(i,a;A)l[i]=a.text;arywrite(l);}}
static immutable MOD=10^^9+7;alias PQueue(T,alias l="b<a")=BinaryHeap!(Array!T,l);import std, core.bitop;
// dfmt on

void main()
{
    long N, K;
    scan(N, K);
    long R, S, P;
    scan(R, S, P);
    auto T = sread();

    auto dp = new long[][](N + 1, 3);
    foreach (i; 0 .. N)
    {
        if (i < K)
        {
            switch (T[i])
            {
            case 'r':
                dp[i + 1][2] = P;
                break;
            case 's':
                dp[i + 1][0] = R;
                break;
            case 'p':
                dp[i + 1][1] = S;
                break;
            default:
                assert(0);
            }
        }
        else
        {
            // dprint(i - K);
            foreach (j; 0 .. 3)
                dp[i + 1][j] = dp[i + 1 - K].reduce!max;
            switch (T[i])
            {
            case 'r':
                dp[i + 1][2] = max(dp[i + 1 - K][0], dp[i + 1 - K][1]) + P;
                break;
            case 's':
                dp[i + 1][0] = max(dp[i + 1 - K][1], dp[i + 1 - K][2]) + R;
                break;
            case 'p':
                dp[i + 1][1] = max(dp[i + 1 - K][0], dp[i + 1 - K][2]) + S;
                break;
            default:
                assert(0);
            }
        }
    }
    dp[$ - K .. $].map!(reduce!max).sum().writeln();
}
