{"raw_statement":[{"iden":"problem statement","content":"There are $N$ squares arranged in a row from left to right. The height of the $i$\\-th square from the left is $H_i$.\nFor each square, you will perform either of the following operations once:\n\n*   Decrease the height of the square by $1$.\n*   Do nothing.\n\nDetermine if it is possible to perform the operations so that the heights of the squares are non-decreasing from left to right."},{"iden":"constraints","content":"*   All values in input are integers.\n*   $1 \\leq N \\leq 10^5$\n*   $1 \\leq H_i \\leq 10^9$"},{"iden":"input","content":"Input is given from Standard Input in the following format:\n\n$N$\n$H_1$ $H_2$ $...$ $H_N$"},{"iden":"sample input 1","content":"5\n1 2 1 1 3"},{"iden":"sample output 1","content":"Yes\n\nYou can achieve the objective by decreasing the height of only the second square from the left by $1$."},{"iden":"sample input 2","content":"4\n1 3 2 1"},{"iden":"sample output 2","content":"No"},{"iden":"sample input 3","content":"5\n1 2 3 4 5"},{"iden":"sample output 3","content":"Yes"},{"iden":"sample input 4","content":"1\n1000000000"},{"iden":"sample output 4","content":"Yes"}],"translated_statement":null,"sample_group":[],"show_order":["default"],"formal_statement":null,"simple_statement":null,"has_page_source":true}