int上限是2147483647，乘积最大是2500000000

所以要开long long(题目也提醒过)

#include<bits/stdc++.h>
using namespace std;
long long a,b;
int main(){
	cin>>a>>b;
	cout<<a*b;
	return 0;
}

#include<bits/stdc++.h>
#define ll long long

using namespace std;

int main(){
	ll a, b;
	cin >> a >> b;
	cout << a* b;
	return 0;
}