Id	1758
Title	Minimizing maximizer
Tags	dp segment tree
Brief solution	dp[i][j]表示考虑前i个sorter,完成1到j的排序的最少个数.考虑第i+1个sorter,其左右端是x,y,于是可以用min(dp[i][x...y])+1来更新dp[i+1][y],其它dp[i+1][j]=dp[i][j].