50分求助，一到14就错，谢谢

    #include<iostream>
using namespace std;
int a[250], b[250], c[300], i, j, k,a_len,p,c_len;
int main()
{
    int n;
    cin >> n;
    for (i = 1; i <= n; i++)
    {
        p = i;
        a_len = -1;
        while (p > 0)
        {
            a_len++;
            a[a_len] = p % 10;
            p /= 10;
        }
        for (j = 0; j <= a_len ; j++)//gs
        {
            for (k = 1; k < i; k++)
            {
                a[j] *= k;
            }
            c[j] += a[j];
        }
        for (k = 0; k < 250; k++)
        {
            if (c[k] >= 10)
            {
                c[k + 1] += c[k]/10;
                c[k] %= 10;
            }
        }
    }
    c_len = 250;
    while(c[c_len-1]==0)
            c_len--;
    for (j = c_len-1; j >=0 ; j--)
        cout << c[j];
    return 0;
}