package yukicoder; import java.util.Scanner; public class Main { public static void main(String[] args) { new Main().solver(); } void solver() { Scanner sc = new Scanner(System.in); int N = sc.nextInt(); for (int i = 0; i < 2020; i++) { for (int j = 0; j < 2020; j++) { memo[i][j] = -1; } } long ans=0; for(int i=0;i0)return 0; if(a==0&&b==0)throw new AssertionError("error"); long sum = 0; for (int i = 1; i <= a; i++) { sum += dp(b + i - 1, a - i); sum%=MOD; } return memo[a][b]=sum; } }