#include<iostream>
using namespace std;
int main()
{
int n,m,s=0,x,i;
while(cin>>n>>m)
{
if(n<m)
{
while(s<m)
{
i=0;
x=n+i;
s+=x;
i+=1;
}
cout<<x-n+1<<endl;
}
else
{
cout<<0<<endl;
}
}
return 0;
}