#include<iostream>
using namespace std; 
int main(){
    double a,b;
    int c;
    scanf("%lf %lf",&a,&b);
    c =a*b*0.1;
    c =(c+5)/10*10;
    printf("%d",c);
    return 0;
}

#include #include using namespace std; int(){ double a,b; scanf("%lf %lf",&a,&b); c = ab0.1; c = (c+5)/10*10; printf("%d",c); return 0;

#include<iostream>
using namespace std; 
int main(){
    double a,b;
    int c;
    scanf("%lf %lf",&a,&b);
    c =a*b*0.1;
    c =(c+5)/10*10;
    printf("%d",c);
    return 0;
}