HJ5

var str = readline()
var six = {
    '0':0,
    '1':1,
    '2':2,
    '3':3,
    '4':4,
    '5':5,
    '6':6,
    '7':7,
    '8':8,
    '9':9,
    'A':10,
    'B':11,
    'C':12,
    'D':13,
    'E':14,
    'F':15
} 

function mul(n){
    let mulit = 1
    while(n){
        mulit *= 16
        n--
    }
    return mulit
}


function fn(str){
    let str2 = str.slice(2).split('').reverse()
    let num = 0
    for(let i=0 ; i<str2.length ; i++){
        num += six[str2[i]]*mul(i)
    }
    return num
}

let res = fn(str)
console.log(res)