#include <stdio.h>
int main(){
    int year,hour;
    double money;
    if (scanf("%d %d",&year,&hour)!=EOF){
        //printf("%d %d\n",year,hour);
        // 分析不敲钟的时间
        if (year<5){
            if (hour<=40){money=hour*30.0;}
            else{money=1200+(hour-40)*45.0;}
        }else{
            if (hour<=40){money=hour*50.0;}
            else{money=2000+(hour-40)*75.0;}
        }
        printf("%.2f\n",money);
    }
    else{
        printf("input wrong");
    }
    return 0;
}