Compilare: user.cpp: In function ‘void solving()’: user.cpp:54:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] FORN(i, a.length()) ^ user.cpp:30:33: note: in definition of macro ‘FORN’ #define FORN(i,n) for(int i=0;i<n;++i) ^ user.cpp:56:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] FOR(j, i+1, a.length()) ^ user.cpp:31:35: note: in definition of macro ‘FOR’ #define FOR(i,a,b) for(int i=a;i<=b;++i) ^ user.cpp:27:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] #define X first ^ user.cpp:61:43: note: in expansion of macro ‘X’ if (a.substr(i, j - i).length() > ans.X) ^ user.cpp:27:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] #define X first ^ user.cpp:70:49: note: in expansion of macro ‘X’ else if (a.substr(i, j - i).length() == ans.X) ^