运行结果没对（用的666666*99999999)

抱着试试的心态上了洛谷，自己挑不出啥毛病，求助

#include<iostream>
#include<cstdio>
#include<algorithm>
#include<cmath>
#include<string> 
using namespace std;
string cmp(string a,string b){
	if(a.length()>b.length()){
		return a;
	}
	if(b.length()<a.length()){
		return b;
	}
	int i;
	for(i=1;i<=a.length();i++){
		if(a[i]>b[i]){
			return a;
		}
		if(b[i]>a[i]){
			return b;
		}
	}
	if(i==(a.length()+1)){
		return a;
	}
}
int main(){
	string a,b,c,e,min;
	cin>>a>>b;
	min=cmp(a,b);
	if(min==b){
		swap(a,b);
	}
	for(int i=1;i<=a.length();i++){
		c[0]=0;
		for(int j=1;j<=b.length();j++){
			e[i]=(a[i]*b[j])/10+c[j-1];
			c[j]=(a[i]*b[j])%10;
		}
	}
	for(int i=1;i<=e.length();i++){
		cout<<e[i];
	}
	return 0;
}