ATM Problem doubt

This is my code but i dont know what is wrong with it.
Link to problem : Contest Page | CodeChef

#include
#include
using namespace std;

int main()
{
int x;
float y,sum=0;
cin>>x>>y;
if(x>y)
{
cout<<fixed<<setprecision(2)<<y;
}
else if(x%5==0)
{
if(x>y)
{
cout<<fixed<<setprecision(2)<<y;
}
else if(x<y)
{
sum=y-x-0.50;
cout<<fixed<<setprecision(2)<<sum;
}
}
return 0;
}

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