#include <stdio.h>

int arr[2000][1000];

void generate(int len) {
    int i, j;
    for (i = 0; i < 2*len+2; i++) {
        for (j = 0; j < len+2; j++) {
            arr[i][j] = 0;
        }
    }
    arr[0][0] = 1;
    for (i = 1; i <= len; i++) {
        for (j = 0; j <= i; j++) {
            if (j-1 >= 0) arr[i][j] += arr[i-1][j-1];
            if (j+1 < i) arr[i][j] += arr[i-1][j+1];
        }
    }
    for (i = len-1; i >= 0; i--) {
        for (j = 0; j < len; j++) {
            if (j-1 >= 0) arr[2*len-i][j] += arr[2*len-i-1][j-1];
            if (j+1 < 2*len-i) arr[2*len-i][j] += arr[2*len-i-1][j+1];
        }
    }
    /*
    for (i = 0; i < 2*len+2; i++) {
        for (j = 0; j < len+2; j++) {
            printf("%d ", arr[i][j]);
        }
        printf("\n");
    }
    */
    printf("len %d: %d\n", len, arr[2*len][0]);
}

int main() {
    int i;
    for (i = 1; i <= 10; i++) {
        generate(i);
    }
    return 0;
}