Compilare: user.cpp: In function ‘void Solve()’: user.cpp:24:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k = 1;k < a.length();++k) ~~^~~~~~~~~~~~ user.cpp:29:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (right < a.length() && a[right] == a[right - left]) ~~~~~~^~~~~~~~~~~~ user.cpp:42:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (right < a.length() && a[right] == a[right - left]) ~~~~~~^~~~~~~~~~~~ user.cpp: In function ‘void Write()’: user.cpp:55:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = len;i < a.length();++i) ~~^~~~~~~~~~~~ user.cpp:54:15: warning: unused variable ‘k’ [-Wunused-variable] int cnt = 0, k = 0; ^