#include <stdio.h>

int main() {
    double val = 0.0;
    int month, day, Preferential = 0;
    scanf("%lf %d %d %d", &val, &month, &day, &Preferential);
    if (11 == month && 11 == day) {
        val = val * 0.7;
        if (Preferential == 1)
            val = val - 50;
    }
    if (12 == month && 12 == day) {
        val = val * 0.8;
        if (Preferential == 1)
            val = val - 50;
    }
            printf("%.2lf\n", val>0?val:0.0);

    return 0;
}

商家不会找你钱翻译:优惠完不可能钱是负数