import core.bitop, std.algorithm, std.ascii, std.bigint, std.conv, std.math,
    std.functional, std.numeric, std.range, std.stdio, std.string, std.random,
    std.typecons, std.container, std.format;

// dfmt off
T lread(T = long)(){return readln.chomp.to!T();}
T[] aryread(T = long)(){return readln.split.to!(T[])();}
void scan(TList...)(ref TList Args){auto line = readln.split();
foreach (i, T; TList){T val = line[i].to!(T);Args[i] = val;}}
alias sread = () => readln.chomp();enum MOD = 10 ^^ 9 + 7;
alias PQueue(T, alias less = "a<b") = BinaryHeap!(Array!T, less);
// dfmt on

void main()
{
    long N, K;
    scan(N, K);
    long R, S, P;
    scan(R, S, P);
    string T = sread();
    auto dp = new long[][](N + 1 + K, 3);
    foreach (i; 0 .. N)
    {
        dp[i + K][0] = max(dp[i][1], dp[i][2]) + ((T[i] == 's') ? R : 0);
        dp[i + K][1] = max(dp[i][0], dp[i][2]) + ((T[i] == 'p') ? S : 0);
        dp[i + K][2] = max(dp[i][0], dp[i][1]) + ((T[i] == 'r') ? P : 0);
    }
    long ans;
    foreach (i; 0 .. K)
    {
        ans += max(dp[N + K - 1 - i][0], dp[N + K - 1 - i][1], dp[N + K - 1 - i][2]);
    }
    writeln(ans);
}
