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

void main()
{
    long a, b, c;
    readf("%d %d %d", &a, &b, &c);

    if (a - b >= c)
    {
        writeln(0);
    }
    else
    {
        writeln(c - (a - b));
    }
}
