#include //#include using namespace std; //using namespace atcoder; typedef long long ll; //typedef modint1000000007 mint; const int MOD = 1000000007; #define all(x) x.begin(), x.end() #define rep(i, n) for (int i = 0; i < (int)(n); i++) const int inf = 1 << 30; const ll INF = 1LL << 60; const int dx[8] = {1, 0, -1, 0, -1, -1, 1, 1}; const int dy[8] = {0, 1, 0, -1, -1, 1, -1, 1}; template bool chmax(T& a, const T& b) { if (a < b) { a = b; return 1; } return 0; } template bool chmin(T& a, const T& b) { if (b < a) { a = b; return 1; } return 0; } int main(){ int n; cin >> n; vector a(n); rep(i, n) cin >> a[i]; vector vec; rep(i, n) if(a[i] > 0) vec.push_back(i); ll ans = 0; int x = 0; rep(i, n){ if(a[i] == 0){ ans += abs(vec[x] - i); a[vec[x]]--; a[i]++; if(a[vec[x]] == 0) x++; } } cout << ans << endl; return 0; }