import std.algorithm, std.array, std.container, std.range;
import std.string, std.conv;
import std.math, std.bigint, std.bitmanip, std.random;
import std.stdio, std.typecons;

const auto mod = 10^^9;

void main()
{
  auto rd = readln.split.map!(to!int);
  auto x = rd[0], y = rd[1], d = rd[2];

  if (d <= x + y) {
    auto r = d + 1;
    r -= max(d - y, 0);
    r -= max(d - x, 0);
    writeln(r);
  } else {
    writeln(0);
  }
}