为什么这题快速幂会WA最后一个点啊？

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll Powerr(ll a,ll b)
{
    int prod=1;
    while (b)
    {	
        if (b%2==1)
        {
            prod*=a;
        }
        a*=a;
        b/=2;
    }
    return prod;
} 
int main ()
{
    ll n,m;
    cin>>n>>m;
    int ans=0,x=1;
    while(Powerr(x,m)<=n)
    {
        ans++;
        x++;
    }
    cout<<ans;
}