#include<stdio.h>
int main()
{
    int a,b,c;
    if((scanf("%d\n%d\n%d",&a,&b,&c)!=2))
    {
        printf("Invalid input");
        return 0;
    }
    if(a>b){
        printf("Insufficient balance");
    }
    else{
        printf("%.2f",b-a);
    }
}