#include <stdio.h> #include<string.h> #define M 1000000 int f[M+1]; int main() { int i,j,co,n; memset(f,0,sizeof(f)); co=1; for(i=2;i<=M;i++) { if(f[i]==0) { for(j=i;j<=M;j+=i) f[j]=co; co++; } } while(scanf("%d",&n)!=EOF) { printf("%d\n",f[n]); } return 0; }