C :

#include <stdio.h>
int main()
{
	int n1,n2,num,i,step;
	while(scanf("%d%d",&n1,&n2)!=EOF)
	{
		num=n2-n1;
		i=1;
		step=0;
		if(num==0)
		printf("%d\n",num);
		else
		while(1)
		{
			num-=i;
			step++;
			if(num<=0)
			{
				printf("%d\n",step);
				break;
			}
			num-=i;
			step++;
			if(num<=0)
			{
				printf("%d\n",step);
				break;
			}
			i++;
		}
	}
	return 0;
}

C++ :

#include <bits/stdc++.h>
using namespace std;
int main()
{
	long long x1,x2;
	while(~scanf("%lld%lld",&x1,&x2)){
		
		long long cha=x2-x1;
		long long step=0;
		
		if (cha==0){
			printf("0\n");
			continue;
		}
		
		while((step*step)<=cha){
			step++;
		}
		
		/* prlong longf("%lld\n",step*0);
		prlong longf("%lld\n",step*1);
		prlong longf("%lld\n",step*2); */
		
		
		if (cha- (step*step) >=0){
			cha -= (step*step);
		} else{
			step--;
			cha -= (step*step);
		}
	
		
		if (cha==0){
			printf("%lld\n",step*2-1);
			continue;
		}
		
		
		long long ans=step;
		if (cha%step>0){
			ans+=((cha/step)+1);
		} else ans+=(cha/step);
		
		if (step>1) ans+=step-1;
		
		printf("%lld\n",ans);
		
	}
	return 0;
}