#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<stdint.h>
#include<tgmath.h>
#include<stdbool.h>
#include<sys/queue.h>
#include<time.h>
#define ll long long
#define min(a, b) ((a) > (b) ? (b) : (a))
#define max(a, b) ((a) > (b) ? (a) : (b))

ll a, b, c;
main(){
    scanf("%lld %lld.%lld", &a, &b, &c);
    printf("%lld\n", a*(100*b+c)/100);
    return 0;
}