poj 3673 Cow Multiplication

#include<iostream>#include<string.h>using namespace std;int main(){    int sum=0,l1=0,l2=0;    char a[10]={0},b[10]={0};    cin>>a>>b;    l1=strlen(a);    l2=strlen(b);    for(int i=0;i<l1;i++)    {        for(int j=0;j<l2;j++)        { sum+=(a[i]-'0')*(b[j]-'0');        }    }    cout<<sum<<endl;    return 0;}