import std.conv, std.functional, std.range, std.stdio, std.string;
import std.algorithm, std.array, std.bigint, std.bitmanip, std.complex, std.container, std.math, std.mathspecial, std.numeric, std.regex, std.typecons;
import core.bitop;

class EOFException : Throwable { this() { super("EOF"); } }
string[] tokens;
string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; }
int readInt() { return readToken.to!int; }
long readLong() { return readToken.to!long; }
real readReal() { return readToken.to!real; }

bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } }
bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } }

int binarySearch(alias pred, T)(in T[] as) { int lo = -1, hi = cast(int)(as.length); for (; lo + 1 < hi; ) { const mid = (lo + hi) >> 1; (unaryFun!pred(as[mid]) ? hi : lo) = mid; } return hi; }
int lowerBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a >= val)); }
int upperBound(T)(in T[] as, T val) { return as.binarySearch!(a => (a > val)); }


int root(int[] uf, int u) {
  return (uf[u] < 0) ? u : (uf[u] = uf.root(uf[u]));
}
bool connect(int[] uf, int u, int v) {
  u = uf.root(u);
  v = uf.root(v);
  if (u == v) return false;
  if (uf[u] > uf[v]) swap(u, v);
  uf[u] += uf[v];
  uf[v] = u;
  return true;
}


void main() {
  try {
    for (; ; ) {
      const N = readInt();
      auto A = new int[N];
      foreach (i; 0 .. N) {
        A[i] = readInt();
      }
      
      const lim = A.maxElement + 1;
      auto uf = new int[lim];
      uf[] = -1;
      int ans;
      int l = 0, r = lim, dec = 0;
      foreach (i; 0 .. N) {
        const a = uf.root(A[i]) - dec;
        if (a > 0) {
          ++ans;
          debug {
            writeln(i, ": ", a);
          }
          if (2 * a <= r - l) {
            /*
              0 1 2 3 4 5 6 7
              0 1 2 0 1 2 3 4
                    0 1 2 3 4
            */
            foreach (u; l .. l + a) {
              const r0 = uf.root(u);
              const r1 = uf.root(u + a);
              uf[r0] = r1;
            }
            l += a;
            dec += a;
          } else if (a <= r - l) {
            /*
              0 1 2 3 4
              0 1 2 0 1
              0 1 2
            */
            foreach (u; l .. r - a) {
              const r0 = uf.root(u);
              const r1 = uf.root(u + a);
              uf[r1] = r0;
            }
            r = l + a;
          } else {
            /*
              0 1
              0 1
            */
          }
        }
      }
      writeln(ans);
      
      debug {
        int brt;
        auto as = A.dup;
        writeln(as);
        foreach (i; 0 .. N) {
          const a = as[i];
          if (a > 0) {
            ++brt;
            foreach (j; i .. N) {
              if (as[j] >= a) {
                as[j] -= a;
              }
            }
            writeln("[brt] ", i, ": ", a, "; ", as);
          }
        }
        writeln("brt = ", brt);
      }
    }
  } catch (EOFException e) {
  }
}