#include<stdio.h>
int main()
{
    double paymentAmount, accountBalance;
    int isActive;
    if(scanf("lf%lf%d",&paymentAmount,&accountBalance,&isActive) !=3)
    {
        printf("Invalid input\n");
        return 0;
    }
    if(isActive != 0 && isActive != 1)
    {
        printf("Invalid input\n");
        return 0;
    }
    if(isActive == 0)
    {
        printf("Invalid input\n");
        return 0;
    }
    if (paymentAmount > accountBalance)
    {
        printf("Insufficient Balance\n");
        return 0;
    }
    double remainingBalance = accountBalance- paymentAmount;
    printf("%.2f\n", remainingBalance);
    return 0;
}