https://www.luogu.com.cn/problem/P5717#submit

#include<iostream>
#include<iomanip>
#include<cstdio>
#include<cmath>
#include<algorithm>
#include<cstring>
#include<string>
using namespace std;
int main(){
    int a,b,c;
    cin>>a>>b>>c;
    if(a+b<=c||a+c<=b||b+c<=a||a-b>=c||a-c>=b||b-c>=a){
    	cout<<"Not triangle"<<endl;
    	return 0;
	}else if(a*a+b*b==c*c){
		cout<<"Right triangle"<<endl;
	}else if(a*a+b*b>c*c){
		cout<<"Acute triangle"<<endl;
	}else if(a*a+b*b<c*c){
		cout<<"Obtuse triangle"<<endl;//Obtuse
	}else if(a==b||b==c||a==c){
		cout<<"Isosceles triangle"<<endl;
	}else if(a==b&&b==c){
		cout<<"Equilateral triangle";
	}
	return 0;
}