diff --git a/HDOJ/1556.cpp b/HDOJ/1556.cpp
new file mode 100644
index 0000000..9ac48cd
--- /dev/null
+++ b/HDOJ/1556.cpp
@@ -0,0 +1,132 @@
+/// General includes
+#include <cstdio>
+#include <cstdlib>
+#include <cstring>
+
+#include <algorithm>
+using namespace std;
+/// 延迟更新: 区间运算更新(加法), 区间运算(求和)
+namespace LazySegmentTree
+{
+
+const int MAXN = 100100;
+const int MAXTREENODE = MAXN << 2;
+
+struct node
+{
+    int lt,rt;
+    int val;
+    int add;
+};
+
+node tree[MAXTREENODE];
+
+void _internal_PushUp(int _indexer)
+{
+    tree[_indexer].val=tree[_indexer<<1].val+tree[_indexer<<1|1].val;
+}
+void _internal_PushDown(int _indexer)
+{
+    if(tree[_indexer].add!=0)
+    {
+        /// Broadcast this add value to Left and Right sub-tree node.
+        tree[_indexer<<1].add+=tree[_indexer].add;
+        tree[_indexer<<1|1].add+=tree[_indexer].add;
+        /// Confirm this change by calculate and add changes to sub-trees.
+        tree[_indexer<<1].val+=tree[_indexer].add * (tree[_indexer<<1].rt-tree[_indexer<<1].lt+1);
+        tree[_indexer<<1|1].val+=tree[_indexer].add *(tree[_indexer<<1|1].rt-tree[_indexer<<1|1].lt+1);
+        /// Now Clear this node's add value.
+        tree[_indexer].add=0;
+    }
+}
+
+void build(int L,int R,int _indexer=1)
+{
+    tree[_indexer].lt=L;
+    tree[_indexer].rt=R;
+    tree[_indexer].add=0;/// This must be set to 0.
+    if(L==R)
+    {
+        //scanf("%d",&tree[_indexer].val);
+        tree[_indexer].val = 0;
+        return;
+    }
+    int mid=(L+R)>>1;
+    build(L,mid,_indexer<<1);
+    build(mid+1,R,_indexer<<1|1);
+    /// Update this val from down to up. (>.<)
+    _internal_PushUp(_indexer);
+}
+
+void update(int L,int R,int ValToAdd,int _indexer=1)
+{
+    /// Return when L or R exceeds range. So smart !
+    if(R<tree[_indexer].lt||L>tree[_indexer].rt) return;
+    if(L<=tree[_indexer].lt&&R>=tree[_indexer].rt)
+    {
+        /// This range is covered. So just add the 'add' value, which is called "LAZY"
+        tree[_indexer].add+=ValToAdd;
+        tree[_indexer].val+=ValToAdd*(tree[_indexer].rt-tree[_indexer].lt+1);
+        return;
+    }
+    _internal_PushDown(_indexer);
+    /// This ... Hum.. Seems not so clever...
+    update(L,R,ValToAdd,_indexer<<1);
+    update(L,R,ValToAdd,_indexer<<1|1);
+    _internal_PushUp(_indexer);
+}
+
+int ans;
+void basic_query(int L,int R,int _indexer=1)
+{
+    /// Data to find is not in this range.
+    if(R<tree[_indexer].lt||L>tree[_indexer].rt) return;
+    /// Data to find is right in this range , or covers this range.
+    if(L<=tree[_indexer].lt&&R>=tree[_indexer].rt)
+    {
+        ans+=tree[_indexer].val;
+        return ;
+    }
+    _internal_PushDown(_indexer);
+    int mid=(tree[_indexer].lt+tree[_indexer].rt)>>1;
+    if(R<=mid)
+        basic_query(L,R,_indexer<<1);
+    else if(L>mid)
+        basic_query(L,R,_indexer<<1|1);
+    else
+    {
+        basic_query(L,mid,_indexer<<1);
+        basic_query(mid+1,R,_indexer<<1|1);
+    }
+}
+int query(int L,int R)
+{
+    ans=0;
+    basic_query(L,R);
+    return ans;
+}
+
+}/// End of namespace LazySegmentTree
+
+
+int main()
+{
+    int n;
+    while(scanf("%d",&n)==1&&n!=0)
+    {
+        LazySegmentTree::build(1,n);
+        int x,y;
+        for(int i=0;i<n;i++)
+        {
+            scanf("%d %d",&x,&y);
+            LazySegmentTree::update(x,y,1);
+        }
+        printf("%d",LazySegmentTree::query(1,1));
+        for(int i=2;i<=n;i++)
+        {
+            printf(" %d",LazySegmentTree::query(i,i));
+        }
+        printf("\n");
+    }
+    return 0;
+}