re求助

#include<bits/stdc++.h> 

using namespace std;

int main(){
    char a1[1001] = {},b1[1001] = {};
    int a[1001] = {},b[1001] = {},c[1001] = {};
    cin >> a1 >> b1;
    int lena = strlen(a1);
    int lenb = strlen(b1);
    for(int i = 0; i < lena; i++){
        a[lena - i] = a1[i] - 48;
    }
    for(int i = 0; i < lenb; i++){
        b[lenb - i] = b1[i] - 48;
    }  
    for(int i = 1;i <= lena;i++){
        int x = 0;
        for(int j = 1;j <= lenb;j++){
            c[i+j-1] = a[i] * b[j] + x + c[i+j-1];
            x = c[i + j - 1] / 10;
            c[i+j-1] %= 10; 
        }
        c[i+lenb] = x;
    }
    int lenc = lena + lenb;
    while(c[lenc] == 0 && lenc > 1){
        lenc--;
    }

    for(int i = lenc; i > 0; i--){
        cout << c[i];
    }

    return 0;
}```