import java.util.Scanner;

public class Main {

	@SuppressWarnings("resource")
	public static void main(String args[]) {
		Scanner scanner = new Scanner(System.in);
		int x=scanner.nextInt();
		int y=scanner.nextInt();
		int d=scanner.nextInt();
		long cnt=0;
		for(int i=0;i<=x;i++) {
			int j=d-i;
			if(0<=j&&j<=y) {
				cnt++;
			}
		}
		System.out.println(cnt);
	}
}