Created
July 3, 2021 05:10
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| mod=10**9+7 | |
| def sum_len(l,r): | |
| if r-l==1: | |
| return (len(str(l)))%mod | |
| if l%10!=0: | |
| return (len(str(l))+sum_len(l+1,r))%mod | |
| if r%10!=0: | |
| return (len(str(r-1))+sum_len(l,r-1))%mod | |
| assert l%10==0 | |
| assert r%10==0 | |
| res=sum_len(l//10,r//10)*10+(r-l) | |
| return res%mod | |
| def solve(l,r): | |
| if r-l==1: | |
| return (len(str(l))*l)%mod | |
| if l%10!=0: | |
| return (len(str(l))*l+solve(l+1,r))%mod | |
| if r%10!=0: | |
| return (len(str(r-1))*(r-1)+solve(l,r-1))%mod | |
| assert l%10==0 | |
| assert r%10==0 | |
| res=100*solve(l//10,r//10) | |
| res+=45*sum_len(l//10,r//10) | |
| res+=(r-l)*(l+r-1)//2 | |
| res%=mod | |
| return res | |
| L,R=map(int,input().split()) | |
| print(solve(L,R+1)) |
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