如何解决呀？

#include<bits/stdc++.h>
using namespace std;
int main()
{
	long long a[3];
	for(int i=0;i<3;i++)
		cin>>a[i];
	sort(a,a+3);
	if(a[0]+a[1]<=a[3])
	{
		cout<<"Not triangle";
		return 0;
	}
	if(a[0]*a[0]+a[1]*a[1]==a[2]*a[2])
		cout<<"Right triangle"<<endl;
	else if(a[0]*a[0]+a[1]*a[1]>a[2]*a[2])
		cout<<"Acute triangle"<<endl;
	else if(a[0]*a[0]+a[1]*a[1]<a[2]*a[2])
		cout<<"Obtuse triangle"<<endl;
	if(a[0]==a[1] || a[0]==a[2] || a[1]==a[2])
		cout<<"Isosceles triangle"<<endl;
	if(a[0]==a[1] && a[0]==a[2] && a[1]==a[2])
		cout<<"Equilateral triangle";
	return 0;
}