#include <cstdio>

#include <cmath>

typedef long long LL;

int n;

const int N=;

const LL Inf=0x7fffffff;

LL ans;

int len,prime[N];

bool isnot[N];

inline void getprime(){

    int lim=;

    for(int i=;i<=lim;i++){

        if(!isnot[i])prime[++len]=i;

        for(int j=;prime[j]*i<=lim;j++){

            isnot[prime[j]*i]=;

            if(i%prime[j]==)break;

        }

    }

}

inline bool isprime(int x){

    if(x==)return ;

    int lim=(int)sqrt(x+0.5);

    for(int i=;prime[i]<=lim;i++)

        if(x%prime[i]==)

            return ;

    return ;

}

inline LL Min(LL x,LL y){

    return x<y?x:y;

}

void dfs(int pos,LL now,int rest){

    if(pos>=len)return;

    if(now>=ans)return;

    if(rest==){ans=now;return;}

    if(isprime(rest+)){ans=Min(ans,now*(rest+));return;}

    LL have=prime[pos]-,j=prime[pos];

    if(pos==)have<<=,j<<=;

    while(rest%have==)

        dfs(pos+,now*j,rest/have),have*=prime[pos],j*=prime[pos];

    dfs(pos+,now,rest);

}

int main(){

    getprime(),scanf("%d",&n),ans=Inf+;

    if(n<=){printf("-1");return ;}

    if(n==){printf("");return ;}

    dfs(,,n);

    printf("%lld",ans==Inf+?-:ans);

}