zigzag.cpp

#include <iostream>
#include <vector>
using namespace std;

int main(){
	vector<int> inputs;
	int	input;
	while(cin>>input)
		inputs.push_back(input);
	int	length = inputs.size();
	length = inputs.size();
	vector<int> A(length, 1);
	vector<int>	tmps(length, 0);
	for(int i=1; i< length; i++)
		for(int j=0; j< i; j++){
			int tmp = inputs[j] - inputs[i];
			if(tmp != 0 && tmp*tmps[j] <= 0 && A[j] + 1 > A[i]){
				A[i] = A[j] + 1;
				tmps[i] = tmp;
			}
		}
	cout<<A[length-1];
	return 0;
}