#include #include #include #include #include #include #include #include #include // require sort next_permutation count __gcd reverse etc. #include // require abs exit atof atoi #include // require scanf printf #include #include // require accumulate #include // require fabs #include #include #include #include // require setw #include // require stringstream #include // require memset #include // require tolower, toupper #include // require freopen #include // require srand #define rep(i,n) for(int i=0;i<(n);i++) #define ALL(A) A.begin(), A.end() #define each(i,c) for(auto i=(c).begin();i!=(c).end();++i) #define exist(s,e) ((s).find(e)!=(s).end()) #define clr(a) memset((a),0,sizeof(a)) #define nclr(a) memset((a),-1,sizoef(a)) #define sz(s) (int)((s).size()) #define INRANGE(x,s,e) ((s)<=(x) && (x)<(e)) #define pb push_back #define MP(x,y) make_pair((x),(y)) #define EPS 1e-6 #define INF 1<<20 using namespace std; typedef long long ll; typedef pair P; int main() { ios_base::sync_with_stdio(0); int N; cin >> N; vector a(N, 0 ); int sum = 0; rep (i, N ) cin >> a[i], sum += a[i]; int res = 0; int h = (int)sqrt(sum+EPS ); rep (i, N ){ int block = (int)max (0, (i < h ? i + 1 : 2*h - (i + 1 ) ) ); res += max(a[i] - block, 0 ); } // end rep cout << res << endl; return 0; }