import java.util.*;

public class Solution {
    public int Jump (int n, int[] A) {
      // 0作为起始点，n-1作为终点
      int step = 0;  // 跨了X步
      int dist = 0;  // 跨了X步最远能到哪个点
      int i = 0;
      while (dist < n-1) {
        int lastDist = dist;
        // X步(i.e.上一步)能跨到的范围内
        while (i <= lastDist) {
          // 跨x+1步最远能到哪个点
          dist = Math.max(i + A[i], dist);
          i++;
        }
        step++;
      }
      
      return step;
    }
}