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) {
    // Return the number of games you can buy
    if(p < 1 && p > 100) return 0;
    if(d < 1 && d > 100) return 0;
    if(m < 1 && m > 100) return 0;
    if(s < 1 && s > 10000) return 0;
    if(m > p) return 0;
    
    var res = 0;
    var currentPrice = p;
    var amount = s;
    while(currentPrice <= amount) {
        res++;
        amount = amount - currentPrice;
        if( currentPrice - d >= m )
            {
                currentPrice = currentPrice - d;
            }
        else {
            currentPrice  = m;
        }
    }
    return res;
}

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");

}