BIg multiply

#include<iostream>
#include<cmath>


using namespace std;

int strlen(char str1[]){
	int i = 0;
	while(str1[i] != '\0')
		i++;
	return i;
}
void strTOnum(char str[],int num[]){
	int len = strlen(str);
	int index = len - 1;
	int i = 0;
	while(index>=0){
		num[i] = str[index] - '0';
		i++;
		index--;
	}
}

char str1[500];
char str2[500];


int main(){

while(cin >> str1 && cin >> str2){
if(str1[0] == '0' || str2[0] == '0'){
	cout << '0' <<'\n';
	continue;
}

int num1[500] = {0};
int num2[500] = {0};
int mul[1000] = {0};


strTOnum(str1,num1);
strTOnum(str2,num2);


int index = 0;
int carry = 0;


int len1 = strlen(str1);
int len2 = strlen(str2);

if(len1>=len2){

for(int i=0;i<len2;i++){
		for(int j =0,k=i;j<len1;j++,k++){

			int m = (num2[i] * num1[j])+carry;
			carry = 0;
			mul[k] += m % 10;
			carry = m / 10;

			index = k;

			}
	}




for(int i=0;i<=index;i++){
	if(mul[i]>9){
		int temp = mul[i];
		mul[i] = temp%10;
		mul[i+1] += temp/10;
		if(i+1==index+1){
			index++;
			break;
		}
	}

}

for(int i=index;i>=0;i--){
	cout << mul[i];

}
cout << '\n';


}

else{

for(int i=0;i<len1;i++){
		for(int j =0,k=i;j<len2;j++,k++){

			int m = (num1[i] * num2[j])+carry;
			carry = 0;
			mul[k] += m % 10;
			carry = m / 10;

			index = k;

			}
	}




for(int i=0;i<=index;i++){
	if(mul[i]>9){
		int temp = mul[i];
		mul[i] = temp%10;
		mul[i+1] += temp/10;
		if(i+1==index+1){
			index++;
			break;
		}
	}

}

for(int i=index;i>=0;i--){
	cout << mul[i];

}
cout << '\n';

}

	}


return 0;


	return 0;
}