#include<bits/stdc++.h> using anmespace std; int main(){ int a,b,d; bool t=1; cin>>a>>b; for(int i=1;i<=a-1;i++){ int c;cin>>c; int e=c-b; if(i=1){ d=e; continue; } if(e!=d)t=0; d=e; b=c; } if(t=1)cout<<"Arithmetic Sequence"; else cout<<"No"; return 0; }