function main(input) {
  let [a, b] = input[0].trim().split(" ").map(i => i);
  a = BigInt(parseInt(a));
  b = BigInt(parseInt(b*100));
  let ans = a * b;
  ans = ans+"";
  
  if(ans.length<=2){
    console.log(0);
  }else{
    const ans1 = ans.slice(0,ans.length-2);
    console.log(ans1);
  }
  
}
main(require('fs').readFileSync('/dev/stdin', 'utf8').trim().split("\n"));