Compilare: user.cpp: In function ‘int main()’: user.cpp:50:17: warning: unused variable ‘c’ [-Wunused-variable] int c = primes2 [f]; ^ user.cpp:71:22: warning: unused variable ‘p’ [-Wunused-variable] bool p = 0; ^ user.cpp:61:37: warning: unused variable ‘ij’ [-Wunused-variable] int sz = primes . size () , ij , ij2; ^~ user.cpp:61:42: warning: unused variable ‘ij2’ [-Wunused-variable] int sz = primes . size () , ij , ij2; ^~~ user.cpp:37:25: warning: unused variable ‘j’ [-Wunused-variable] i64 t , a , b , i , j; ^ user.cpp:38:31: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf (cin , "%lld" , &t); ^ user.cpp:39:24: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf (cin , "\n"); ^ user.cpp:43:48: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf (cin , "%lld %lld \n" , &a , &b); ^