#include<stdio.h>
int main()
{
    double paymentAmount,accountBalance;
    int isActive;
    if scanf("%f",&paymentAmount)!=1||
    scanf("%f",&accountBalance)!=1
    scanf("%d",&isActive)!=1
    {
        printf("Invalid input");
        return 0;
    }
    if (paymentAmount <0||paymentAmount>1000000)||accountBalance<0||accountBalance>1000000||(isActive !=0&& isActive))
    {
        printf("Invalid input");
        return 0;
    }
    if (isActive == 0)
    {
        printf("Insufficient Balance");
        return 0;
    }
    float remainBalance = accountBalance-paymentAmount;
    printf("%.2f",remainingBalance);
    return 0;
}