import std.algorithm;
import std.array;
import std.conv;
import std.math;
import std.range;
import std.stdio;
import std.string;
import std.typecons;

T read(T)() { return readln.chomp.to!T; }
T[] reads(T)() { return readln.split.to!(T[]); }
alias readint = read!int;
alias readints = reads!int;

int calc(int a, int b, int c, int d) {
    for (int i = a; i >= 0; i--) {
        if (i * c <= b && i + i * c <= d) {
            return i;
        }
    }
    return 0;
}

void main() {
    auto xs = readints;
    int a = xs[0], b = xs[1], c = xs[2], d = xs[3];
    writeln(calc(a, b, c, d));
}