function solve(input) {
    let text = '';
    for (let i = 0; i < input.length; i++) {
        let [command, value] = input[i].split(' ');

        if (command === 'End') {
            break;
        }
        if (command === 'Add') {
            text += value;
        }
        if (command === 'Upgrade') {
            let ascii = value.charCodeAt(0);
            let char = String.fromCharCode(ascii + 1);
            let arr = text.split('');
            for (let i = 0; i < arr.length; i++) {
                if (arr[i] === value) {
                    arr[i] = char;
                }
            }
            text = arr.join('');
        }
        if (command === 'Print') {
            console.log(text);
        }
        if (command === 'Index') {
            let indeces = [];

            for (let i = 0; i < text.length; i++) {
                if (text[i] === value) {
                    indeces.push(i);
                }
            }
            console.log(indeces.join(' '));
        }
        if (command === 'Remove') {
            let arr = text.split(value);
            text = arr.join('');

        }
    }
}