import std;

void scan(T...)(ref T a) {
    string[] ss = readln.split;
    foreach (i, t; T) a[i] = ss[i].to!t;
}
T read(T)() { return readln.chomp.to!T; }
T[] reads(T)() { return readln.split.to!(T[]); }
alias readint = read!int;
alias readints = reads!int;

void main() {
    double x, y, r; scan(x, y, r);

    double ans = ceil(abs(x) + abs(y) + r * sqrt(2.0));
    writeln(ans);
}