为什么全WA

#include<bits/stdc++.h>
using namespace std;
int n,a[1000005],su[1000005][3];
int dfs(int wz,int tl){int th=1e9;
	if(su[wz][tl])return su[wz][tl];if(wz>=n)return 0;
	if(tl>0)th=min(th,dfs(wz+1,tl-1));
	th=min(th,dfs(wz+1,tl+(tl==2?:0,1))+a[wz]);
	return su[wz][tl]=th;
}
int main(){
	cin>>n;for(int i=1;i<=n;i++)cin>>a[i];
	cout<<dfs(1,2);
	return 0;
}