#include <bits/stdc++.h>
int main() {
  int SLength, BAdd, SLeft, SRight;
  std::cin >> SLength >> BAdd >> SLeft >> SRight;
  int Size = SRight - SLeft + 1;
  int Start = SLeft % (SLength + BAdd);
  int Answer;
  if (Start > SLength) {
    Answer = 1;
    if (Start + Size - 1 <= BAdd + SLength) {
      std::cout << 1;
    } else {
      int BCell = SLength + BAdd - Start + 1;
      int Rest = Size - BCell;
      if (Rest >= SLength) {
        Answer = 1 + SLength;
        int used = SLength + BCell;
        Rest = Size - used;
        int difference = SLength - BAdd;
        if (difference <= 0) {
          std::cout << Answer;
        } else {
          if (difference >= Rest) {
            std::cout << Answer;
          } else {
            int new1 = std::min(SLength - difference, Rest - difference);
            std::cout << Answer + new1;
          }
        }
      } else {
        std::cout << 1 + Rest;
      }
    }
  } else {
    if (Start + Size - 1 <= SLength) {
      std::cout << Size;
    } else {
      int RCell = SLength - Start + 1;
      Answer = RCell;
      int Rest = Size - RCell;
      if (Rest <= BAdd) {
        std::cout << RCell;
      } else {
        Rest = Rest - BAdd;
        if (Rest >= SLength) {
          int difference = SLength - BAdd;
          if (difference <= 0) {
            std::cout << SLength + 1;
          } else {
            std::cout << SLength + difference;
          }
        } else {
          int back = SLength - RCell;
          if (Rest < back) {
            std::cout << RCell + Rest;
          } else {
            int difference = SLength - BAdd;
            if (difference <= 0) {
              if (RCell <= 1) {
                std::cout << Rest + 1;
              } else {
                Answer = RCell + Rest;
                difference = Rest + RCell - SLength;
                if (difference > 0) {
                  std::cout << Answer - difference;
                } else {
                  std::cout << Answer;
                }
              }
            } else {
              std::cout << Rest + std::min(difference, RCell);
            }
          }
        }
      }
    }
  }
  return 0;
}

### Prompt

Your task is to create a Cpp solution to the following problem:

Sometimes Mister B has free evenings when he doesn't know what to do. Fortunately, Mister B found a new game, where the player can play against aliens.

All characters in this game are lowercase English letters. There are two players: Mister B and his competitor.

Initially the players have a string s consisting of the first a English letters in alphabetical order (for example, if a = 5, then s equals to "abcde").

The players take turns appending letters to string s. Mister B moves first.

Mister B must append exactly b letters on each his move. He can arbitrary choose these letters. His opponent adds exactly a letters on each move.

Mister B quickly understood that his opponent was just a computer that used a simple algorithm. The computer on each turn considers the suffix of string s of length a and generates a string t of length a such that all letters in the string t are distinct and don't appear in the considered suffix. From multiple variants of t lexicographically minimal is chosen (if a = 4 and the suffix is "bfdd", the computer chooses string t equal to "aceg"). After that the chosen string t is appended to the end of s.

Mister B soon found the game boring and came up with the following question: what can be the minimum possible number of different letters in string s on the segment between positions l and r, inclusive. Letters of string s are numerated starting from 1.

Input

First and only line contains four space-separated integers: a, b, l and r (1 ≤ a, b ≤ 12, 1 ≤ l ≤ r ≤ 109) — the numbers of letters each player appends and the bounds of the segment.

Output

Print one integer — the minimum possible number of different letters in the segment from position l to position r, inclusive, in string s.

Examples

Input

1 1 1 8


Output

2

Input

4 2 2 6


Output

3

Input

3 7 4 6


Output

1

Note

In the first sample test one of optimal strategies generate string s = "abababab...", that's why answer is 2.

In the second sample test string s = "abcdbcaefg..." can be obtained, chosen segment will look like "bcdbc", that's why answer is 3.

In the third sample test string s = "abczzzacad..." can be obtained, chosen, segment will look like "zzz", that's why answer is 1.

### Response

```cpp
#include <bits/stdc++.h>
int main() {
  int SLength, BAdd, SLeft, SRight;
  std::cin >> SLength >> BAdd >> SLeft >> SRight;
  int Size = SRight - SLeft + 1;
  int Start = SLeft % (SLength + BAdd);
  int Answer;
  if (Start > SLength) {
    Answer = 1;
    if (Start + Size - 1 <= BAdd + SLength) {
      std::cout << 1;
    } else {
      int BCell = SLength + BAdd - Start + 1;
      int Rest = Size - BCell;
      if (Rest >= SLength) {
        Answer = 1 + SLength;
        int used = SLength + BCell;
        Rest = Size - used;
        int difference = SLength - BAdd;
        if (difference <= 0) {
          std::cout << Answer;
        } else {
          if (difference >= Rest) {
            std::cout << Answer;
          } else {
            int new1 = std::min(SLength - difference, Rest - difference);
            std::cout << Answer + new1;
          }
        }
      } else {
        std::cout << 1 + Rest;
      }
    }
  } else {
    if (Start + Size - 1 <= SLength) {
      std::cout << Size;
    } else {
      int RCell = SLength - Start + 1;
      Answer = RCell;
      int Rest = Size - RCell;
      if (Rest <= BAdd) {
        std::cout << RCell;
      } else {
        Rest = Rest - BAdd;
        if (Rest >= SLength) {
          int difference = SLength - BAdd;
          if (difference <= 0) {
            std::cout << SLength + 1;
          } else {
            std::cout << SLength + difference;
          }
        } else {
          int back = SLength - RCell;
          if (Rest < back) {
            std::cout << RCell + Rest;
          } else {
            int difference = SLength - BAdd;
            if (difference <= 0) {
              if (RCell <= 1) {
                std::cout << Rest + 1;
              } else {
                Answer = RCell + Rest;
                difference = Rest + RCell - SLength;
                if (difference > 0) {
                  std::cout << Answer - difference;
                } else {
                  std::cout << Answer;
                }
              }
            } else {
              std::cout << Rest + std::min(difference, RCell);
            }
          }
        }
      }
    }
  }
  return 0;
}

```