import std.stdio,
       std.conv,
       std.string,
       std.range,
       std.math,
       std.algorithm;

void main()
{
    auto input = stdin.byLine.join(" ").split.to!(int[]);
    auto Aw = input[0], Ab = input[1],
         Bw = input[2], Bb = input[3],
         C  = input[4], D  = input[5];

    (Aw - max(C - Ab, 0) + min(Bw + max(C - Ab, 0), D)).writeln;
}