#include<stdio.h>
int main(void){
    int N;      //  number of stars
    int K;      //  rank when solved
    double point;   //  midway calculation
    int total;

    scanf("%d %d",&N,&K);

    point = (50*N)/(0.8+0.2*K);

    total = 50*N + (int)point;

    printf("%d\n",total);

    return 0;
}