Compilare: user.cpp: In function 'void sift(int)': user.cpp:26: warning: comparison between signed and unsigned integer expressions user.cpp:30: warning: comparison between signed and unsigned integer expressions user.cpp:33: warning: comparison between signed and unsigned integer expressions user.cpp: In function 'int main()': user.cpp:96: warning: comparison between signed and unsigned integer expressions user.cpp:113: warning: comparison between signed and unsigned integer expressions user.cpp:116: warning: comparison between signed and unsigned integer expressions /tmp/ccv6vFhL.o: In function `main': user.cpp:(.text+0x40c): warning: the `gets' function is dangerous and should not be used.