这个代码怎么是0分

#include <stdio.h>
#include <string.h>

char x[5005], y[5005];
int a[5005], b[5005], c[5005], la, lb, lc;
int main()
{
    gets(x);
    gets(y);
    la = strlen(x);
    lb = strlen(y);
    for (int i = 0; i < la; i++)
        a[la - i] = x[i] - '0';
    for (int i = 0; i < lb; i++)
        b[lb - i] = y[i] - '0';
    for (int i = 0; i <= la; i++)
    {
        for (int j = 0; j <= lb; j++)
        {
            c[i + j - 1] += a[i] * b[j];
            c[i + j] = c[i + j - 1] / 10;
            c[i + j - 1] %= 10;
        }
    }
    lc = la + lb;
    if (c[lc + 1] > 0)
        lc++;
    while (c[lc] == 0 && lc > 1)
        lc--;
    for (int i = lc; i > 0; i--)
        printf("%d", c[i]);
    return 0;
}