别人不开longlong见祖宗了，而我没有见祖宗，怎么回事

#include <iostream>
#include <math.h>
#include <string>
using namespace std;
int prime[]={2,3,5,7,11,13,17,23,29,31,37,41,43,47};
int ci[50];

int main(){
	int n,a,c;
	cin>>n;
	while (n--){
		cin>>a;
		for (int i=0;i<=13;i++){
			c=0;
			while (a&&a%prime[i]==0){
				c++;
				a/=prime[i];
			}
			ci[prime[i]]=max(ci[prime[i]],c);
		}
	}
	int ans=1;
	for (int i=0;i<=13;i++) ans*=pow(prime[i],ci[prime[i]]);
	cout<<ans;
}