1 #include<bits/stdc++.h> 2 using namespace std; 3 const int maxn=1e3+5; 4 const int mod=1e9+7; 5 int n,m,mark; 6 char l[maxn],r[maxn]; 7 int numl,numr; 8 int tot,e[maxn]; 9 long long c[maxn][20][2]; 10 template<class t>void red(t &x) 11 { 12 int w=1; 13 x=0; 14 char ch=getchar(); 15 while(ch>'9'||ch<'0') 16 { 17 if(ch=='-') 18 w=-1; 19 ch=getchar(); 20 } 21 while(ch>='0'&&ch<='9') 22 { 23 x=(x<<3)+(x<<1)+ch-'0'; 24 ch=getchar(); 25 } 26 x*=w; 27 } 28 void input() 29 { 30 freopen("input.txt","r",stdin); 31 } 32 void dv(int x) 33 { 34 tot=0; 35 while(x) 36 { 37 e[++tot]=x%10; 38 x/=10; 39 } 40 e[tot+1]=0; 41 } 42 long long dfs(int pos,bool limit,bool zero,int pre,int qpre,bool dc) 43 { 44 if(pos==0) 45 return dc; 46 if(!limit&&c[pos][pre][dc]!=-1) 47 return c[pos][pre][dc]; 48 int up=limit?e[pos]:9; 49 long long ans=0; 50 for(int i=0;i<=up;++i) 51 ans+=dfs(pos-1,limit&&(i==up),zero||i,i,zero?pre:-1,dc||(i==pre&&zero)||(i==qpre&&zero))%mod; 52 if(!limit&&zero&&qpre!=-1) 53 c[pos][pre][dc]=ans; 54 return ans; 55 } 56 long long solve() 57 { 58 //dv(x); 59 tot=0; 60 while(m--) 61 e[++tot]=r[m]-'0'; 62 while(!e[tot]) 63 --tot; 64 memset(c,-1,sizeof(c)); 65 long long ans=dfs(tot,1,0,-1,-1,0)%mod; 66 tot=0; 67 while(n--) 68 e[++tot]=l[n]-'0'; 69 while(!e[tot]) 70 --tot; 71 memset(c,-1,sizeof(c)); 72 ans-=dfs(tot,1,0,-1,-1,0)%mod; 73 return ans; 74 } 75 void read() 76 { 77 scanf("%s%s",l,r); 78 n=strlen(l); 79 m=strlen(r); 80 } 81 void work() 82 { 83 int i=1; 84 while(l[n-i]=='0'&&n>i) 85 { 86 l[n-i]='9'; 87 ++i; 88 } 89 l[n-i]-=1; 90 printf("%lld",(solve()+mod)%mod); 91 } 92 int main() 93 { 94 //input(); 95 read(); 96 work(); 97 return 0; 98 }