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 howManyGames(p, d, m, s) {
    let gamesAmount = 0;
    let lastPrice = p;

    while(s >= lastPrice) {
        lastPrice = p - gamesAmount * d;

        if (lastPrice <= m) {
            lastPrice = m;
        }

        s -= lastPrice;

        gamesAmount++;
    }

    return gamesAmount;
}

function main() {
    var p_temp = readLine().split(' ');
    var p = parseInt(p_temp[0]);
    var d = parseInt(p_temp[1]);
    var m = parseInt(p_temp[2]);
    var s = parseInt(p_temp[3]);
    var answer = howManyGames(p, d, m, s);
    process.stdout.write("" + answer + "\n");

}