问题描述 |
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Andrewid the Android is a galaxy-famous detective. In his free time he likes to think about strings containing zeros and ones. Once he thought about a string of length $$n$$ consisting of zeroes and ones. Consider the following operation: we choose any two adjacent positions in the string, and if one them contains $$0$$, and the other contains $$1$$, then we are allowed to remove these two digits from the string, obtaining a string of length $$n-2$$ as a result. Now Andreid thinks about what is the minimum length of the string that can remain after applying the described operation several times (possibly, zero)? Help him to calculate this number. |

输入描述 |

First line of the input contains a single integer $$n$$ ($$1 \leq n \leq 2 \times 10^5$$), the length of the string that Andreid has. The second line contains the string of length $$n$$ consisting only from zeros and ones. |

输出描述 |

Output the minimum length of the string that may remain after applying the described operations several times. |

样例输入复制样例 |

4 1100 |

样例输出 |

0 |

提示说明 |

In the first sample test it is possible to change the string like the following: 1100->10->(empty) |

来源 |

Codeforces Round 310 (Div. 2) Problem A |

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