#include<cstdio>

typedef long long i64;

const int P=1e9+,g=,sqrt5=,I2=(P+)/,B=;

const int r1=(P++sqrt5)/,r2=(P+-sqrt5)/;

const int lr1=,lr2=;

inline int mul(int a,int b){return (i64)a*b%P;}

inline void muls(int&a,int b){a=mul(a,b);}

inline int fix(int x){return x+(x>>&P);}

int pw(int a,int n){

    int v=;

    for(;n;n>>=,muls(a,a))if(n&)muls(v,a);

    return v;

}

void exgcd(int a,int b,int&x,int&y){

    if(!b){x=,y=;return;}

    exgcd(b,a%b,y,x);

    y-=a/b*x;

}

int inv(int a,int b){

    int x,y;

    exgcd(a,b,x,y);

    return (x%b+b)%b;

}

int gcd(int a,int b){return b?gcd(b,a%b):a;}

int solve(int a,int b,int c,int tp){

    if(!a)return b?-:-tp;

    int g=gcd(a,c);

    if(b%g)return -;

    a/=g,b/=g,c/=g;

    i64 t=(i64)b*inv(a,c)%c;

    if(!t)t=c;

    if(t%!=tp)t+=c;

    return t%!=tp?-:t;

}

int h[][];

int&at(int x){

    int w=x&;

    while(h[w][]){

        if(h[w][]==x)return h[w][];

        w=(w+)&;

    }

    h[w][]=x;

    return h[w][];

}

void pre(){

    int v=;

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

        at(v)=i+;

        muls(v,g);

    }

}

int log(int x){

    int t=pw(g,P--B);

    for(int i=;;i+=B){

        int y=at(x);

        if(y)return y-+i;

        muls(x,t);

    }

}

int sqrt(int x){

    int t=log(x);

    return t&?-:pw(g,t/);

}

int ans=-;

void upd(int v){

    if(~v&&(v<ans||ans==-))ans=v;

}

void cal(int x,int tp){

    upd(solve(lr1,log(x),P-,tp));

    upd(solve(lr2,log(fix(-x)),P-,tp));

}

int main(){

    pre();

    int v;

    scanf("%d",&v);

    if(!v)return puts("-1"),;

    muls(v,sqrt5);

    int v2=mul(v,v);

    int s1=sqrt(fix(v2-)),s2=sqrt(fix(v2+-P));

    if(~s1){

        cal(mul(fix(v+s1-P),I2),);

        cal(mul(fix(v-s1),I2),);

    }

    if(~s2){

        cal(mul(fix(v+s2-P),I2),);

        cal(mul(fix(v-s2),I2),);

    }

    return printf("%d\n",ans),;

}