Compilare: user.cpp: In function ‘int solve2()’: user.cpp:80:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s.size(); i++) ^ user.cpp:90:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int step = 1; step < s.size(); step++) ^ user.cpp:91:46: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0, j = step; i < s.size() && j < s.size(); i++,j++) { ^ user.cpp:91:62: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0, j = step; i < s.size() && j < s.size(); i++,j++) { ^