{"raw_statement":[{"iden":"problem statement","content":"For a positive integer $X$, let $f(X)$ be the number of positive divisors of $X$.\nGiven a positive integer $N$, find $\\sum_{K=1}^N K\\times f(K)$."},{"iden":"constraints","content":"*   $1 \\leq N \\leq 10^7$"},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$"},{"iden":"sample input 1","content":"4"},{"iden":"sample output 1","content":"23\n\nWe have $f(1)=1$, $f(2)=2$, $f(3)=2$, and $f(4)=3$, so the answer is $1\\times 1 + 2\\times 2 + 3\\times 2 + 4\\times 3 =23$."},{"iden":"sample input 2","content":"100"},{"iden":"sample output 2","content":"26879"},{"iden":"sample input 3","content":"10000000"},{"iden":"sample output 3","content":"838627288460105\n\nWatch out for overflows."}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}