import std;

alias sread = () => readln.chomp();
alias lread = () => readln.chomp.to!long();
alias aryread(T = long) = () => readln.split.to!(T[]);
//aryread!string();
//auto PS = new Tuple!(long,string)[](M);
//x[]=1;でlong[]全要素1に初期化
void main()
{
    long n, a, b;
    scan(n, a, b);
    // writeln(n, a, b);
    // writeln("a-1:", a - 1);
    // writeln("n-b:", n - b);
    if (((a - 1) == (n - b)) && (a + b) % 2 == 0)
    {
        writeln((a + b) / 2 - a);
        return;
    }
    if ((a - 1) > (n - b))
    {
        writeln(n - a);
    }
    else if ((a - 1) < (b - 1))
    {
        writeln(b - 1);
    }

}

void scan(L...)(ref L A)
{
    auto l = readln.split;
    foreach (i, T; L)
    {
        A[i] = l[i].to!T;
    }
}

void arywrite(T)(T a)
{
    a.map!text.join(' ').writeln;
}
