#pragma GCC optimize ("Ofast") #include using namespace std; #define MD 1000000007 void *wmem; char memarr[96000000]; template inline S min_L(S a,T b){ return a<=b?a:b; } struct mint{ static unsigned md; static unsigned W; static unsigned R; static unsigned Rinv; static unsigned mdninv; static unsigned RR; unsigned val; mint(){ } mint(int a){ val = mulR(a); } mint(unsigned a){ val = mulR(a); } mint(long long a){ val = mulR(a); } mint(unsigned long long a){ val = mulR(a); } int get_inv(long long a, int md){ long long t=a; long long s=md; long long u=1; long long v=0; long long e; while(s){ e=t/s; t-=e*s; u-=e*v; swap(t,s); swap(u,v); } if(u<0){ u+=md; } return u; } void setmod(unsigned m){ int i; unsigned t; W = 32; md = m; R = (1ULL << W) % md; RR = (unsigned long long)R*R % md; switch(m){ case 104857601: Rinv = 2560000; mdninv = 104857599; break; case 998244353: Rinv = 232013824; mdninv = 998244351; break; case 1000000007: Rinv = 518424770; mdninv = 2226617417U; break; case 1000000009: Rinv = 171601999; mdninv = 737024967; break; case 1004535809: Rinv = 234947584; mdninv = 1004535807; break; case 1007681537: Rinv = 236421376; mdninv = 1007681535; break; case 1012924417: Rinv = 238887936; mdninv = 1012924415; break; case 1045430273: Rinv = 254466304; mdninv = 1045430271; break; case 1051721729: Rinv = 257538304; mdninv = 1051721727; break; default: Rinv = get_inv(R, md); mdninv = 0; t = 0; for(i=(0);i<((int)W);i++){ if(t%2==0){ t+=md; mdninv |= (1U<> W); if(t >= md){ t -= md; } return t; } unsigned reduce(unsigned long long T){ unsigned m = (unsigned)T * mdninv; unsigned t = (unsigned)((T + (unsigned long long)m*md) >> W); if(t >= md){ t -= md; } return t; } unsigned get(){ return reduce(val); } mint &operator+=(mint a){ val += a.val; if(val >= md){ val -= md; } return *this; } mint &operator-=(mint a){ if(val < a.val){ val = val + md - a.val; } else{ val -= a.val; } return *this; } mint &operator*=(mint a){ val = reduce((unsigned long long)val*a.val); return *this; } mint &operator/=(mint a){ return *this *= a.inverse(); } mint operator+(mint a){ return mint(*this)+=a; } mint operator-(mint a){ return mint(*this)-=a; } mint operator*(mint a){ return mint(*this)*=a; } mint operator/(mint a){ return mint(*this)/=a; } mint operator+(int a){ return mint(*this)+=mint(a); } mint operator-(int a){ return mint(*this)-=mint(a); } mint operator*(int a){ return mint(*this)*=mint(a); } mint operator/(int a){ return mint(*this)/=mint(a); } mint operator+(long long a){ return mint(*this)+=mint(a); } mint operator-(long long a){ return mint(*this)-=mint(a); } mint operator*(long long a){ return mint(*this)*=mint(a); } mint operator/(long long a){ return mint(*this)/=mint(a); } mint operator-(void){ mint res; if(val){ res.val=md-val; } else{ res.val=0; } return res; } operator bool(void){ return val!=0; } operator int(void){ return get(); } operator long long(void){ return get(); } mint inverse(){ int a = val; int b = md; int u = 1; int v = 0; int t; mint res; while(b){ t = a / b; a -= t * b; swap(a, b); u -= t * v; swap(u, v); } if(u < 0){ u += md; } res.val = (unsigned long long)u*RR % md; return res; } mint pw(unsigned long long b){ mint a(*this); mint res; res.val = R; while(b){ if(b&1){ res *= a; } b >>= 1; a *= a; } return res; } bool operator==(int a){ return mulR(a)==val; } bool operator!=(int a){ return mulR(a)!=val; } } ; unsigned mint::md; unsigned mint::W; unsigned mint::R; unsigned mint::Rinv; unsigned mint::mdninv; unsigned mint::RR; mint operator+(int a, mint b){ return mint(a)+=b; } mint operator-(int a, mint b){ return mint(a)-=b; } mint operator*(int a, mint b){ return mint(a)*=b; } mint operator/(int a, mint b){ return mint(a)/=b; } mint operator+(long long a, mint b){ return mint(a)+=b; } mint operator-(long long a, mint b){ return mint(a)-=b; } mint operator*(long long a, mint b){ return mint(a)*=b; } mint operator/(long long a, mint b){ return mint(a)/=b; } inline void rd(int &x){ int k; int m=0; x=0; for(;;){ k = getchar_unlocked(); if(k=='-'){ m=1; break; } if('0'<=k&&k<='9'){ x=k-'0'; break; } } for(;;){ k = getchar_unlocked(); if(k<'0'||k>'9'){ break; } x=x*10+k-'0'; } if(m){ x=-x; } } inline void rd(mint &x){ int i; rd(i); x=i; } inline void wt_L(char a){ putchar_unlocked(a); } inline void wt_L(int x){ int s=0; int m=0; char f[10]; if(x<0){ m=1; x=-x; } while(x){ f[s++]=x%10; x/=10; } if(!s){ f[s++]=0; } if(m){ putchar_unlocked('-'); } while(s--){ putchar_unlocked(f[s]+'0'); } } inline void wt_L(mint x){ int i; i = (int)x; wt_L(i); } template struct Matrix{ int r; int c; int mem; T *dat; Matrix(){ r=c=mem = 0; } Matrix(const int rr, const int cc){ if(rr == 0 || cc == 0){ r = c = 0; } else{ r = rr; c = cc; } mem = r * c; if(mem > 0){ dat = new T[mem]; } } Matrix(const Matrix &a){ int i; r = a.r; c = a.c; mem = r * c; dat = new T[mem]; for(i=(0);i<(mem);i++){ dat[i] = a.dat[i]; } } ~Matrix(){ if(mem){ delete [] dat; } } void changeSize(const int rr, const int cc){ if(rr==0 || cc==0){ r = c = 0; } else{ r = rr; c = cc; } if(mem < r*c){ if(mem){ delete [] dat; } mem = r*c; dat = new T[mem]; } } Matrix& operator=(const Matrix &a){ int i; int j; r = a.r; c = a.c; mem = r * c; dat = new T[mem]; for(i=(0);i<(mem);i++){ dat[i] = a.dat[i]; } return *this; } Matrix& operator=(const int a){ int i; int j; j = r * c; for(i=(0);i<(j);i++){ dat[i] = 0; } j =min_L(r, c); for(i=(0);i<(j);i++){ dat[i*c+i] = a; } return *this; } Matrix& operator+=(const Matrix &a){ int i; int j; if(r==0 || r!=a.r || c!=a.c){ changeSize(0,0); return *this; } j = r*c; for(i=(0);i<(j);i++){ dat[i] += a.dat[i]; } return *this; } Matrix operator+(const Matrix &a){ return Matrix(*this) += a; } Matrix& operator-=(const Matrix &a){ int i; int j; if(r==0 || r!=a.r || c!=a.c){ changeSize(0,0); return *this; } j = r*c; for(i=(0);i<(j);i++){ dat[i] -= a.dat[i]; } return *this; } Matrix operator-(const Matrix &a){ return Matrix(*this) -= a; } Matrix& operator*=(const Matrix &a){ int i; int j; int k; int x; T *m; if(r==0 || c!=a.r){ changeSize(0,0); return *this; } m = (T*)wmem; x = r * a.c; for(i=(0);i<(x);i++){ m[i] = 0; } for(i=(0);i<(r);i++){ for(k=(0);k<(c);k++){ for(j=(0);j<(a.c);j++){ m[i*a.c+j] += dat[i*c+k] * a.dat[k*a.c+j]; } } } changeSize(r, a.c); for(i=(0);i<(x);i++){ dat[i] = m[i]; } return *this; } Matrix operator*(const Matrix &a){ return Matrix(*this) *= a; } Matrix& operator*=(const int a){ int i; int j; j = r * c; for(i=(0);i<(j);i++){ dat[i] *= a; } return *this; } Matrix& operator*=(const long long a){ int i; int j; j = r * c; for(i=(0);i<(j);i++){ dat[i] *= a; } return *this; } Matrix& operator*=(const double a){ int i; int j; j = r * c; for(i=(0);i<(j);i++){ dat[i] *= a; } return *this; } inline T* operator[](const int a){ return dat+a*c; } } ; template Matrix operator*(const int a, const Matrix &b){ return Matrix(b)*=a; } template Matrix operator*(const Matrix &b, const int a){ return Matrix(b)*=a; } template Matrix operator*(const long long a, const Matrix &b){ return Matrix(b)*=a; } template Matrix operator*(const Matrix &b, const long long a){ return Matrix(b)*=a; } template Matrix operator*(const double a, const Matrix &b){ return Matrix(b)*=a; } template Matrix operator*(const Matrix &b, const double a){ return Matrix(b)*=a; } template inline Matrix pow_L(Matrix a, S b){ int i; int j; Matrix res; res.changeSize(a.r, a.c); res = 1; while(b){ if(b&1){ res *= a; } b >>= 1; a *= a; } return res; } template inline T pow_L(T a, S b){ T res = 1; res = 1; while(b){ if(b&1){ res *= a; } b >>= 1; a *= a; } return res; } inline double pow_L(double a, double b){ return pow(a,b); } int N; mint A; mint B; int main(){ wmem = memarr; { mint x; x.setmod(MD); } Matrix m; rd(A); rd(B); rd(N); m.changeSize(2,2); m[0][0] = 0; m[0][1] = 1; m[1][0] = B; m[1][1] = A; (m = pow_L(m,N)); wt_L(m[0][1]); wt_L('\n'); return 0; } // cLay varsion 20190921-1 // --- original code --- // int N; // mint A, B; // { // Matrix m; // rd(A,B,N); // m.changeSize(2,2); // m[0][0] = 0; // m[0][1] = 1; // m[1][0] = B; // m[1][1] = A; // m **= N; // wt(m[0][1]); // }