#pragma GCC optimize ("Ofast") #include using namespace std; inline int my_getchar_unlocked(){ static char buf[1048576]; static int s = 1048576; static int e = 1048576; if(s == e && e == 1048576){ e = fread_unlocked(buf, 1, 1048576, stdin); s = 0; } if(s == e){ return EOF; } return buf[s++]; } inline void rd(int &x){ int k; int m=0; x=0; for(;;){ k = my_getchar_unlocked(); if(k=='-'){ m=1; break; } if('0'<=k&&k<='9'){ x=k-'0'; break; } } for(;;){ k = my_getchar_unlocked(); if(k<'0'||k>'9'){ break; } x=x*10+k-'0'; } if(m){ x=-x; } } inline void rd(long long &x){ int k; int m=0; x=0; for(;;){ k = my_getchar_unlocked(); if(k=='-'){ m=1; break; } if('0'<=k&&k<='9'){ x=k-'0'; break; } } for(;;){ k = my_getchar_unlocked(); if(k<'0'||k>'9'){ break; } x=x*10+k-'0'; } if(m){ x=-x; } } struct MY_WRITER{ char buf[1048576]; int s; int e; MY_WRITER(){ s = 0; e = 1048576; } ~MY_WRITER(){ if(s){ fwrite_unlocked(buf, 1, s, stdout); } } } ; MY_WRITER MY_WRITER_VAR; void my_putchar_unlocked(int a){ if(MY_WRITER_VAR.s == MY_WRITER_VAR.e){ fwrite_unlocked(MY_WRITER_VAR.buf, 1, MY_WRITER_VAR.s, stdout); MY_WRITER_VAR.s = 0; } MY_WRITER_VAR.buf[MY_WRITER_VAR.s++] = a; } inline void wt_L(char a){ my_putchar_unlocked(a); } inline void wt_L(const char c[]){ int i=0; for(i=0;c[i]!='\0';i++){ my_putchar_unlocked(c[i]); } } int N; long long A[200000]; long long s; int main(){ int i; rd(N); { int Lj4PdHRW; for(Lj4PdHRW=(0);Lj4PdHRW<(N);Lj4PdHRW++){ rd(A[Lj4PdHRW]); } } for(i=(0);i<(N);i++){ if(A[i] > i+1){ wt_L("No"); wt_L('\n'); return 0; } } for(i=(N)-1;i>=(0);i--){ if( (A[i] + s) % (i+1) ){ wt_L("No"); wt_L('\n'); return 0; } s += (A[i] + s) / (i+1); } wt_L("Yes"); wt_L('\n'); return 0; } // cLay varsion 20200813-1 [beta] // --- original code --- // int N; ll A[2d5], s; // { // rd(N,A(N)); // rep(i,N) if(A[i] > i+1) wt("No"), return 0; // rrep(i,N){ // if( (A[i] + s) % (i+1) ) wt("No"), return 0; // s += (A[i] + s) / (i+1); // } // wt("Yes"); // }