#include <stdio.h>

int main(void) {
    long int A, b2;
    double B, C;
    long int result;
    
    scanf("%ld", &A);
    scanf("%lf", &B);
    b2 = B * 100;
    C = A * b2;
    result = C/100;
    printf("%ld\n", result);
    return 0;
}