import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = Integer.parseInt(sc.next());
		int b = Integer.parseInt(sc.next());
		int c = Integer.parseInt(sc.next());
		int ans;
		int free = a - b;
		if (free > 0) {
			if (free > c) {
				ans = 0;
			} else {
				ans = c - free;
			}
		} else {
			ans = c;
		}
		System.out.println(ans);
	}

} import java.util.Scanner; Scanner java.util public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = Integer.parseInt(sc.next());
		int b = Integer.parseInt(sc.next());
		int c = Integer.parseInt(sc.next());
		int ans;
		int free = a - b;
		if (free > 0) {
			if (free > c) {
				ans = 0;
			} else {
				ans = c - free;
			}
		} else {
			ans = c;
		}
		System.out.println(ans);
	}

} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = Integer.parseInt(sc.next());
		int b = Integer.parseInt(sc.next());
		int c = Integer.parseInt(sc.next());
		int ans;
		int free = a - b;
		if (free > 0) {
			if (free > c) {
				ans = 0;
			} else {
				ans = c - free;
			}
		} else {
			ans = c;
		}
		System.out.println(ans);
	} main {
		Scanner sc = new Scanner(System.in);
		int a = Integer.parseInt(sc.next());
		int b = Integer.parseInt(sc.next());
		int c = Integer.parseInt(sc.next());
		int ans;
		int free = a - b;
		if (free > 0) {
			if (free > c) {
				ans = 0;
			} else {
				ans = c - free;
			}
		} else {
			ans = c;
		}
		System.out.println(ans);
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = Integer.parseInt(sc.next()); a Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int b = Integer.parseInt(sc.next()); b Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int c = Integer.parseInt(sc.next()); c Integer.parseInt(sc.next()) Integer.parseInt Integer sc.next() sc.next sc int ans; ans int free = a - b; free a - b a b if (free > 0) {
			if (free > c) {
				ans = 0;
			} else {
				ans = c - free;
			}
		} else {
			ans = c;
		} free > 0 free 0 {
			if (free > c) {
				ans = 0;
			} else {
				ans = c - free;
			}
		} if (free > c) {
				ans = 0;
			} else {
				ans = c - free;
			} free > c free c {
				ans = 0;
			} ans = 0 ans 0 {
				ans = c - free;
			} ans = c - free ans c - free c free {
			ans = c;
		} ans = c ans c System.out.println(ans) System.out.println System.out System System.out ans String[] args args public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = Integer.parseInt(sc.next());
		int b = Integer.parseInt(sc.next());
		int c = Integer.parseInt(sc.next());
		int ans;
		int free = a - b;
		if (free > 0) {
			if (free > c) {
				ans = 0;
			} else {
				ans = c - free;
			}
		} else {
			ans = c;
		}
		System.out.println(ans);
	}

} public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = Integer.parseInt(sc.next());
		int b = Integer.parseInt(sc.next());
		int c = Integer.parseInt(sc.next());
		int ans;
		int free = a - b;
		if (free > 0) {
			if (free > c) {
				ans = 0;
			} else {
				ans = c - free;
			}
		} else {
			ans = c;
		}
		System.out.println(ans);
	}

} Main
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int a = Integer.parseInt(sc.next());
		int b = Integer.parseInt(sc.next());
		int c = Integer.parseInt(sc.next());
		int ans;
		int free = a - b;
		if (free > 0) {
			if (free > c) {
				ans = 0;
			} else {
				ans = c - free;
			}
		} else {
			ans = c;
		}
		System.out.println(ans);
	}

}
