uva 10170

#include<stdio.h>
int main()
{
    long int s,d,i,n;
    while(scanf("%ld%ld",&s,&d)==2)
    {
        n=0;
        for(i=s;;i++)
        {
            n=n+i;
            if(n>=d)
            {
                printf("%ld\n",i);
                break;
            }
        }
    }
    return 0;
}