C++ :

#include<iostream>
using namespace std;
int main(){
	int a,b,c;
	cin>>a>>b>>c;
	if(a+b>c){
		if(a+c>b){
			if(b+c>a){
				cout<<"Yes";
			}
		}
	}
	else{
		cout<<"No";
	}
	return 0;
}

Python :

# coding=utf-8
a=int(input())
b=int(input())
c=int(input())
if a+b>c and a+c>b and b+c>a:
    print("Yes")
else:
    print("No")