x=1000000 L=1000 Primelist=[i for i in range(x+1)] Primelist[1]=0 # 1は素数でないので0にする. for i in Primelist: if i>L: break if i==0: continue for j in range(2*i,x+1,i): Primelist[j]=0 Primes=[Primelist[j] for j in range(x+1) if Primelist[j]!=0] N=int(input()) ANS=0 for p in Primes: if p<=N: ANS+=p print(ANS)