Compilare: user.cpp: In function ‘int main()’: user.cpp:24:44: warning: suggest parentheses around ‘+’ inside ‘<<’ [-Wparentheses] for(j=(((i*i)<<1) + (i<<1)); (j<<1 +1)<=nmax; j+=(i<<1)+1 ) ^ user.cpp:32:44: warning: suggest parentheses around ‘+’ inside ‘<<’ [-Wparentheses] for(j=(((i*i)<<1) + (i<<1)); (j<<1 +1)<=nmax; j+=(i<<1)+1 ) ^ user.cpp:18:22: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(f,"%d",&n); ^