const rl=require('readline').createInterface({input:process.stdin})
const iter=rl[Symbol.asyncIterator]()
const readline=async()=>(await iter.next()).value
void async function(){
    const lines=parseInt(await readline())
    console.log(lines*1024*1024/4)
    rl.close()
}()

 京公网安备 11010502036488号
京公网安备 11010502036488号