#include<iostream>
using namespace std;
int main(){
	long long a,b,c;
	cin>>a>>b>>c;
	long long sb=a+b+c;//求和
	sb/=2;//最大ab的平均值
	//cout<<sb<<endl;
	long long i;
	for(i=0;i<=1000000000000;i++){
		//cout<<(i*(i+1)/2)<<endl;
		//cout<<((i+1)*(i+2)/2)<<endl;
		if(sb>=(i*(i+1)/2)&&sb<+((i+1)*(i+2)/2)){
			break;
		}
	} 
	cout<<i<<endl;
	return 0;
}