Miscellany

void crivo() {     int i,j;     prime[0]=1;     prime[1]=1;     for (i=4;i<1000001;i+=2) prime[i]=1;     for (i=3;i<=1000;i+=2) {         if (prime[i]==0) {            for (j=i*i;j<1000001;j+=i) prime[j]=1;         }     }}