diff --git a/QUSTOJ/1844_x7536110.cpp b/QUSTOJ/1844_x7536110.cpp
new file mode 100644
index 0000000..0806757
--- /dev/null
+++ b/QUSTOJ/1844_x7536110.cpp
@@ -0,0 +1,156 @@
+#include <cstdio>
+#include <cstring>
+#include <queue>
+#include <cstdlib>
+#include <algorithm>
+#include <vector>
+#include <cmath>
+#include <iostream>
+using namespace std;
+typedef long long LL;
+LL dpyes[25][15],dpno[25][15],ttime[25],num[25],top=0;
+int judge(LL l,LL r)
+{
+    for (int i=r; i>=l; i--)
+    {
+        if (num[i]&1)//odd
+        {
+            LL tt=1;
+            while (i-1>=l&&(num[i-1]&1))i--,tt++;
+            if (i!=l&&tt%2==1) return false;
+        }
+        else
+        {
+            LL tt=1;
+            while (i-1>=l&&!(num[i-1]&1))i--,tt++;
+            if (i!=l&&tt%2==0) return false;
+        }
+    }
+    return true;
+}
+LL cal(LL x)
+{
+    LL res=0;
+    top=0;
+    while (x)
+    {
+        num[++top]=x%10;
+        x/=10;
+    }
+    for (int i=1; i<num[top]; i++) res+=dpyes[top][i];
+    for (int i=1; i<top; i++)
+    {
+        for (int j=1; j<=9; j++)
+        {
+            res+=dpyes[i][j];
+        }
+    }
+// cout<<res<<endl;
+    for (int i=top-1; i>0; i--)
+    {
+        if (!judge(i+1,top)) break;
+        int hh=1,ti=i+1;
+        while (ti+1<=top&&(num[ti+1]%2==num[ti]%2))ti++,hh++;
+        if (num[i+1]&1)//odd
+        {
+            if (hh&1)//odd
+            {
+                for (int j=1; j<num[i];j+=2)
+                {
+                    res+=dpno[i][j];
+                }
+            }
+            else
+            {
+                for (int j=0;j<num[i];j++)
+                {
+                    res+=dpyes[i][j];
+                }
+            }
+        }
+        else
+        {
+            if (hh&1)//odd
+            {
+                for (int j=1;j<num[i];j+=2)
+                {
+                    res+=dpyes[i][j];
+                }
+                for (int j=0;j<num[i];j+=2)
+                {
+                    res+=dpno[i][j];
+                }
+            }
+            else
+            {
+                for (int j=0; j<num[i];j+=2)
+                {
+                    res+=dpyes[i][j];
+                }
+            }
+        }
+    }
+    return res;
+}
+int main()
+{
+    ttime[0]=1;
+    for (int i=1; i<=20; i++) ttime[i]=5*ttime[i-1];
+    dpyes[0][1]=dpyes[0][0]=1;
+    dpyes[1][0]=dpyes[1][2]=dpyes[1][4]=dpyes[1][6]=dpyes[1][8]=1;
+    dpno[1][1]=dpno[1][3]=dpno[1][5]=dpno[1][7]=dpno[1][9]=1;
+    for (int i=2; i<=20; i++)
+    {
+        for (int j=0; j<10; j++)
+        {
+            if (j&1)//odd
+            {
+                for (int k=2; k<=i; k+=2)
+                {
+                    dpyes[i][j]+=dpyes[i-k][0]*ttime[k-1];
+                    dpyes[i][j]+=dpyes[i-k][2]*ttime[k-1];
+                    dpyes[i][j]+=dpyes[i-k][4]*ttime[k-1];
+                    dpyes[i][j]+=dpyes[i-k][6]*ttime[k-1];
+                    dpyes[i][j]+=dpyes[i-k][8]*ttime[k-1];
+                }
+                for (int k=1; k<=i; k+=2)
+                {
+                    dpno[i][j]+=dpyes[i-k][0]*ttime[k-1];
+                    dpno[i][j]+=dpyes[i-k][2]*ttime[k-1];
+                    dpno[i][j]+=dpyes[i-k][4]*ttime[k-1];
+                    dpno[i][j]+=dpyes[i-k][6]*ttime[k-1];
+                    dpno[i][j]+=dpyes[i-k][8]*ttime[k-1];
+                }
+            }
+            else
+            {
+                for (int k=1; k<=i; k+=2)
+                {
+                    dpyes[i][j]+=dpyes[i-k][1]*ttime[k-1];
+                    dpyes[i][j]+=dpyes[i-k][3]*ttime[k-1];
+                    dpyes[i][j]+=dpyes[i-k][5]*ttime[k-1];
+                    dpyes[i][j]+=dpyes[i-k][7]*ttime[k-1];
+                    dpyes[i][j]+=dpyes[i-k][9]*ttime[k-1];
+                }
+                for (int k=2; k<=i; k+=2)
+                {
+                    dpno[i][j]+=dpyes[i-k][1]*ttime[k-1];
+                    dpno[i][j]+=dpyes[i-k][3]*ttime[k-1];
+                    dpno[i][j]+=dpyes[i-k][5]*ttime[k-1];
+                    dpno[i][j]+=dpyes[i-k][7]*ttime[k-1];
+                    dpno[i][j]+=dpyes[i-k][9]*ttime[k-1];
+                }
+            }
+        }
+    }
+    int T,ncas=1;
+    scanf ("%d",&T);
+    while (T--)
+    {
+        LL l,r;
+        scanf ("%lld%lld",&l,&r);
+//        cout<<cal(l+1)<<endl;
+        printf ("Case #%d: %lld\n",ncas++,cal(r+1)-cal(l));
+    }
+    return 0;
+}