#include <iostream> #include <algorithm> #include <cstdio> #include <cmath> using namespace std; const int MAXN = 1e3 + 1e2; int a[MAXN]; int f1[MAXN]; int f2[MAXN]; int n; int main() { scanf("%d", &n); for (int i = 0;i <= n - 1;i++) scanf(" %d", &a[i]); f1[0] = 0; f2[1] = 0; f1[1] = a[0]; f2[2] = a[1]; for (int i = 2;i <= n;i++) f1[i] = min(f1[i - 1] + a[i - 1], f1[i - 2] + a[i - 2]); for (int i = 3;i <= n;i++) f2[i] = min(f2[i - 1] + a[i - 1], f2[i - 2] + a[i - 2]); printf("%d", min(f1[n], f2[n])); return 0; }