process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();    
});

function readLine() {
    return input_stdin_array[input_currentline++];
}

/////////////// ignore above this line ////////////////////

function main() {
    h = readLine().split(' ');
    h = h.map(Number);
    var word = readLine();
    var len = word.length;
    
    var max = 0;
    
    for (var i = 0; i < len; i++) {
        var ch = word.charAt(i).charCodeAt(0) - 97;
        if (h[ch] > max) max = h[ch];
    }
    console.log(len * max)

}