#include <stdio.h>

int factorial(int n);

int NCR(int n, int r);

int s[10002][10002] = {};

int n, r;

int main() {

scanf("%d %d", &n, &r);

printf("%d", NCR(n, r));

}

int NCR(int n, int r) {

if (n == 1 && r == 1) {

s[n][r] = 1;

return 1;

}

if (n == r) {

s[n][r] = 1;

return 1;

}

if (r == 0) {

s[n][r] = 1;

return 1;

}

if (s[n][r] == 0) {

s[n][r] = (NCR(n - 1, r - 1) + NCR(n - 1, r))% 100000007;

return s[n][r];

}

else

return s[n][r];

}