{"problem":{"name":"Streamline","description":{"content":"We will play a one-player game using a number line and $N$ pieces. First, we place each of these pieces at some integer coordinate. Here, multiple pieces can be placed at the same coordinate. Our obje","description_type":"Markdown"},"platform":"AtCoder","limit":{"time_limit":2000,"memory_limit":262144},"difficulty":"None","is_remote":true,"is_sync":true,"sync_url":null,"sign":"abc117_c"},"statements":[{"statement_type":"Markdown","content":"We will play a one-player game using a number line and $N$ pieces.\nFirst, we place each of these pieces at some integer coordinate.\nHere, multiple pieces can be placed at the same coordinate.\nOur objective is to visit all of the $M$ coordinates $X_1, X_2, ..., X_M$ with these pieces, by repeating the following move:\n**Move**: Choose a piece and let $x$ be its coordinate. Put that piece at coordinate $x+1$ or $x-1$.\nNote that the coordinates where we initially place the pieces are already regarded as visited.\nFind the minimum number of moves required to achieve the objective.\n\n## Constraints\n\n*   All values in input are integers.\n*   $1 \\leq N \\leq 10^5$\n*   $1 \\leq M \\leq 10^5$\n*   $-10^5 \\leq X_i \\leq 10^5$\n*   $X_1, X_2, ..., X_M$ are all different.\n\n## Input\n\nInput is given from Standard Input in the following format:\n\n$N$ $M$\n$X_1$ $X_2$ $...$ $X_M$\n\n[samples]","is_translate":false,"language":"English"}],"meta":{"iden":"abc117_c","tags":[],"sample_group":[["2 5\n10 12 1 2 14","5\n\nThe objective can be achieved in five moves as follows, and this is the minimum number of moves required.\n\n*   Initially, put the two pieces at coordinates $1$ and $10$.\n*   Move the piece at coordinate $1$ to $2$.\n*   Move the piece at coordinate $10$ to $11$.\n*   Move the piece at coordinate $11$ to $12$.\n*   Move the piece at coordinate $12$ to $13$.\n*   Move the piece at coordinate $13$ to $14$."],["3 7\n-10 -3 0 9 -100 2 17","19"],["100 1\n-100000","0"]],"created_at":"2026-03-03 11:01:14"}}