import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{
	public static void main(String[] args) throws IOException {
		try (BufferedReader br = new BufferedReader(
				new InputStreamReader(System.in))) {

			String in = br.readLine();
			String chr[] = in.split(" ");
			int a = Integer.parseInt(chr[0]);
			int b = Integer.parseInt(chr[1]);
			int c = Integer.parseInt(chr[2]);
			int ans = (a-b);
			 System.out.println(ans>=c?0:c-ans);
		}
	}
} import java.io.BufferedReader; BufferedReader java.io import java.io.IOException; IOException java.io import java.io.InputStreamReader; InputStreamReader java.io public class Main{
	public static void main(String[] args) throws IOException {
		try (BufferedReader br = new BufferedReader(
				new InputStreamReader(System.in))) {

			String in = br.readLine();
			String chr[] = in.split(" ");
			int a = Integer.parseInt(chr[0]);
			int b = Integer.parseInt(chr[1]);
			int c = Integer.parseInt(chr[2]);
			int ans = (a-b);
			 System.out.println(ans>=c?0:c-ans);
		}
	}
} Main public static void main(String[] args) throws IOException {
		try (BufferedReader br = new BufferedReader(
				new InputStreamReader(System.in))) {

			String in = br.readLine();
			String chr[] = in.split(" ");
			int a = Integer.parseInt(chr[0]);
			int b = Integer.parseInt(chr[1]);
			int c = Integer.parseInt(chr[2]);
			int ans = (a-b);
			 System.out.println(ans>=c?0:c-ans);
		}
	} main {
		try (BufferedReader br = new BufferedReader(
				new InputStreamReader(System.in))) {

			String in = br.readLine();
			String chr[] = in.split(" ");
			int a = Integer.parseInt(chr[0]);
			int b = Integer.parseInt(chr[1]);
			int c = Integer.parseInt(chr[2]);
			int ans = (a-b);
			 System.out.println(ans>=c?0:c-ans);
		}
	} try (BufferedReader br = new BufferedReader(
				new InputStreamReader(System.in))) {

			String in = br.readLine();
			String chr[] = in.split(" ");
			int a = Integer.parseInt(chr[0]);
			int b = Integer.parseInt(chr[1]);
			int c = Integer.parseInt(chr[2]);
			int ans = (a-b);
			 System.out.println(ans>=c?0:c-ans);
		} {

			String in = br.readLine();
			String chr[] = in.split(" ");
			int a = Integer.parseInt(chr[0]);
			int b = Integer.parseInt(chr[1]);
			int c = Integer.parseInt(chr[2]);
			int ans = (a-b);
			 System.out.println(ans>=c?0:c-ans);
		} BufferedReader br = new BufferedReader(
				new InputStreamReader(System.in)) BufferedReader br = new BufferedReader(
				new InputStreamReader(System.in)) new BufferedReader(
				new InputStreamReader(System.in)) String in = br.readLine(); in br.readLine() br.readLine br String chr[] = in.split(" "); chr in.split(" ") in.split in " " int a = Integer.parseInt(chr[0]); a Integer.parseInt(chr[0]) Integer.parseInt Integer chr[0] chr 0 int b = Integer.parseInt(chr[1]); b Integer.parseInt(chr[1]) Integer.parseInt Integer chr[1] chr 1 int c = Integer.parseInt(chr[2]); c Integer.parseInt(chr[2]) Integer.parseInt Integer chr[2] chr 2 int ans = (a-b); ans (a-b) a b System.out.println(ans>=c?0:c-ans) System.out.println System.out System System.out ans>=c?0:c-ans ans>=c ans c 0 c-ans c ans String[] args args public class Main{
	public static void main(String[] args) throws IOException {
		try (BufferedReader br = new BufferedReader(
				new InputStreamReader(System.in))) {

			String in = br.readLine();
			String chr[] = in.split(" ");
			int a = Integer.parseInt(chr[0]);
			int b = Integer.parseInt(chr[1]);
			int c = Integer.parseInt(chr[2]);
			int ans = (a-b);
			 System.out.println(ans>=c?0:c-ans);
		}
	}
} public class Main{
	public static void main(String[] args) throws IOException {
		try (BufferedReader br = new BufferedReader(
				new InputStreamReader(System.in))) {

			String in = br.readLine();
			String chr[] = in.split(" ");
			int a = Integer.parseInt(chr[0]);
			int b = Integer.parseInt(chr[1]);
			int c = Integer.parseInt(chr[2]);
			int ans = (a-b);
			 System.out.println(ans>=c?0:c-ans);
		}
	}
} Main
import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

public class Main{
	public static void main(String[] args) throws IOException {
		try (BufferedReader br = new BufferedReader(
				new InputStreamReader(System.in))) {

			String in = br.readLine();
			String chr[] = in.split(" ");
			int a = Integer.parseInt(chr[0]);
			int b = Integer.parseInt(chr[1]);
			int c = Integer.parseInt(chr[2]);
			int ans = (a-b);
			 System.out.println(ans>=c?0:c-ans);
		}
	}
}