Compilare: main.cpp: In function 'bool divisible(int)': main.cpp:15:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(start < bignr.size()){ ~~~~~~^~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:62:100: warning: narrowing conversion of '(i + ((long int)y))' from 'long int' to 'int' inside { } [-Wnarrowing] int test[] = {*primes.lower_bound(max(x, 7)), *(--primes.upper_bound(y + i)), x, i + y, (x + i + y)/2}; ~~^~~ main.cpp:62:116: warning: narrowing conversion of '(((((long int)x) + i) + ((long int)y)) / 2l)' from 'long int' to 'int' inside { } [-Wnarrowing] int test[] = {*primes.lower_bound(max(x, 7)), *(--primes.upper_bound(y + i)), x, i + y, (x + i + y)/2}; ~~~~~~~~~~~^~