{"raw_statement":[{"iden":"problem statement","content":"You are given a permutation $A=(A_1,\\ldots,A_N)$ of $(1,2,\\ldots,N)$.  \nTransform $A$ into $(1,2,\\ldots,N)$ by performing the following operation between $0$ and $N-1$ times, inclusive:\n\n*   Operation: Choose any pair of integers $(i,j)$ such that $1\\leq i < j \\leq N$. Swap the elements at the $i$\\-th and $j$\\-th positions of $A$.\n\nIt can be proved that under the given constraints, it is always possible to transform $A$ into $(1,2,\\ldots,N)$."},{"iden":"constraints","content":"*   $2 \\leq N \\leq 2\\times 10^5$\n*   $(A_1,\\ldots,A_N)$ is a permutation of $(1,2,\\ldots,N)$.\n*   All input values are integers."},{"iden":"input","content":"The input is given from Standard Input in the following format:\n\n$N$\n$A_1$ $\\ldots$ $A_N$"},{"iden":"sample input 1","content":"5\n3 4 1 2 5"},{"iden":"sample output 1","content":"2\n1 3\n2 4\n\nThe operations change the sequence as follows:\n\n*   Initially, $A=(3,4,1,2,5)$.\n*   The first operation swaps the first and third elements, making $A=(1,4,3,2,5)$.\n*   The second operation swaps the second and fourth elements, making $A=(1,2,3,4,5)$.\n\nOther outputs such as the following are also considered correct:\n\n4\n2 3\n3 4\n1 2\n2 3"},{"iden":"sample input 2","content":"4\n1 2 3 4"},{"iden":"sample output 2","content":"0"},{"iden":"sample input 3","content":"3\n3 1 2"},{"iden":"sample output 3","content":"2\n1 2\n2 3"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}