请问当n = 1200会出现溢出，该怎么改啊，

# include <iostream>
# include <stdlib.h>
# include <cstdio>
# include <cmath>
using namespace std;
int a[1800] = {1};
int cmp(const void* a, const void* b)
{
    return *(int*)a - *(int *)b;
}
int main()
{
    int i, j, k, x = 1,n;
    for(k = 0; k < 12; k ++ )
        for(j = 0; j < 12; j ++ )
            for(i = 0; i < 12; i ++ )
            {
                a[x] = pow(2,i)*pow(3,j)*pow(5,k);
                x ++ ;
            }
    qsort(a,1729,sizeof(a[0]),cmp);
    while(cin >> n && n != 0)
    {
        cout<<a[n]<<endl;
        //printf("%I64d", a[n]);
    }
    return 0;
}