import java.util.*;

public class Main{

  public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();

    if(1<=b && b<=a && a<=20 && 1<=c && c<=20){
      int x = a-b;
      int y = c-x;

      if(y<0){
        System.out.println(0);
      }else{
        System.out.println(y);
      }
    }

  }

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

  public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();

    if(1<=b && b<=a && a<=20 && 1<=c && c<=20){
      int x = a-b;
      int y = c-x;

      if(y<0){
        System.out.println(0);
      }else{
        System.out.println(y);
      }
    }

  }

} Main public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();

    if(1<=b && b<=a && a<=20 && 1<=c && c<=20){
      int x = a-b;
      int y = c-x;

      if(y<0){
        System.out.println(0);
      }else{
        System.out.println(y);
      }
    }

  } main {

    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();

    if(1<=b && b<=a && a<=20 && 1<=c && c<=20){
      int x = a-b;
      int y = c-x;

      if(y<0){
        System.out.println(0);
      }else{
        System.out.println(y);
      }
    }

  } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int a = sc.nextInt(); a sc.nextInt() sc.nextInt sc int b = sc.nextInt(); b sc.nextInt() sc.nextInt sc int c = sc.nextInt(); c sc.nextInt() sc.nextInt sc if(1<=b && b<=a && a<=20 && 1<=c && c<=20){
      int x = a-b;
      int y = c-x;

      if(y<0){
        System.out.println(0);
      }else{
        System.out.println(y);
      }
    } 1<=b && b<=a && a<=20 && 1<=c && c<=20 1<=c a<=20 1<=b && b<=a && a<=20 && 1<=c && c<=20 1<=b 1 b b<=a b a a<=20 a 20 1<=c 1 c c<=20 c 20 {
      int x = a-b;
      int y = c-x;

      if(y<0){
        System.out.println(0);
      }else{
        System.out.println(y);
      }
    } int x = a-b; x a-b a b int y = c-x; y c-x c x if(y<0){
        System.out.println(0);
      }else{
        System.out.println(y);
      } y<0 y 0 {
        System.out.println(0);
      } System.out.println(0) System.out.println System.out System System.out 0 {
        System.out.println(y);
      } System.out.println(y) System.out.println System.out System System.out y String[] args args public class Main{

  public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();

    if(1<=b && b<=a && a<=20 && 1<=c && c<=20){
      int x = a-b;
      int y = c-x;

      if(y<0){
        System.out.println(0);
      }else{
        System.out.println(y);
      }
    }

  }

} public class Main{

  public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();

    if(1<=b && b<=a && a<=20 && 1<=c && c<=20){
      int x = a-b;
      int y = c-x;

      if(y<0){
        System.out.println(0);
      }else{
        System.out.println(y);
      }
    }

  }

} Main
import java.util.*;

public class Main{

  public static void main(String[] args) {

    Scanner sc = new Scanner(System.in);
    int a = sc.nextInt();
    int b = sc.nextInt();
    int c = sc.nextInt();

    if(1<=b && b<=a && a<=20 && 1<=c && c<=20){
      int x = a-b;
      int y = c-x;

      if(y<0){
        System.out.println(0);
      }else{
        System.out.println(y);
      }
    }

  }

}
