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) {
    var dollarsSpent =0;
    var count =0;
    var currentCost =p;
    while (dollarsSpent <= s)
        {
           
            
            if(count ==0)
                {
                    dollarsSpent = p;
                }
            else if(currentCost-d >= m)
                {
                    currentCost -= d;
                    dollarsSpent +=currentCost;
                }
            else{
                currentCost=m;
                dollarsSpent +=currentCost;
            }
            if(dollarsSpent <= s)
            count+=1;
            
             //console.info(s + " " + dollarsSpent + " " + p + " "+ d + " " + currentCost + " " + m);
        }
    return count;
}

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");

}