\using namespace std;
int main(){
    int s1,s2,s3;
    if(!(cin>>s1>>s2>>s3)) return 0;
    if(!(s1+s2>s3&&s1>+s3>s2&&s2+s3>s1){
    cout<<"valid triangle";
}else{
    cout<<"invalid triangle";
}
return 0;
}