E. Clear the Multisettime limit per test2 secondsmemory limit per test256 megabytesinputstandard inputoutputstandard outputYou have a multiset containing several integers. Initially, it contains a_1 elements equal to 1, a_2 elements equal to 2, ..., a_n elements equal to n.You may apply two types of operations:  choose two integers l and r (l \le r), then remove one occurrence of l, one occurrence of l + 1, ..., one occurrence of r from the multiset. This operation can be applied only if each number from l to r occurs at least once in the multiset;  choose two integers i and x (x \ge 1), then remove x occurrences of i from the multiset. This operation can be applied only if the multiset contains at least x occurrences of i. What is the minimum number of operations required to delete all elements from the multiset?InputThe first line contains one integer n (1 \le n \le 5000).The second line contains n integers a_1, a_2, ..., a_n (0 \le a_i \le 10^9).OutputPrint one integer — the minimum number of operations required to delete all elements from the multiset.ExamplesInput
4
1 4 1 1
Output
2
Input
5
1 0 1 0 1
Output
3

4
1 4 1 1

2 
['data structures', 'divide and conquer', 'dp', 'greedy', '*2200']