#include<stdio.h>
int main()
{
	int i,t,arry[10000],key,max,pre,flag;
	while(scanf("%d",&t)!=EOF&&t!=0)
	{
		while(scanf("%d",&arry[1])!=EOF&&arry[1]!=0)
		{
			for(i=2;i<=t;i++)
				scanf("%d",&arry[i]);
			key=1;max=arry[1];pre=0;flag=1;
			while(1)
			{
				for(i=key;(i<max-pre+key)&&(i<=t);i++)
					if(arry[i]!=max-i+key)
					{
						flag=0;
						break;
					}
				if(i==t+1||flag==0)
					break;
				key=i;pre=max;
				if(arry[key]>max)
					max=arry[key];
			}
			if(flag==0)
				printf("No\n");
			else if(flag==1)
				printf("Yes\n");
		}
		printf("\n");
	}
}