#include#include#includeusing namespace std;intn,a[10000];int main(){ cin>>n; for(inti=1;i<=n;i++) cin>>a[i]; for(inti=1;i<=n;i++){ if(a[i]2*i]||a[i]2*i+1]){ cout<<"No"; return 0; } } cout<<"Yes"; return 0;}
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