Sum of Remainders
题目描述
E. Sum of Remainders
time limit per test
2 secondsmemory limit per test
256 megabytesinput
standard inputoutput
standard outputCalculate the value of the sum: n mod 1 + n mod 2 + n mod 3 + ... + n mod m. As the result can be very large, you should print the value modulo 109+7 (the remainder when divided by 109+7).
The modulo operator a mod b stands for the remainder after dividing a by b. For example 10 mod 3 = 1.
Input
The only line contains two integers n,m (1≤n,m≤1013) − the parameters of the sum.
Output
Print integer s − the value of the required sum modulo 109+7.
Examples
Input
3 4
Output
4
Input
4 4
Output
1
Input
1 1
Output
0
题目来源：fps-www.educg.net-codeforce-1-2833.xml.zip；FPS 共享题包，题包内第 920 题。保留原作者与原赛事署名。