Compilare: user.cpp: In function ‘void solve(int)’: user.cpp:27:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1; i <= A[k].length(); i++ ) ~~^~~~~~~~~~~~~~~~ user.cpp:30:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1; i < A[k].length() - 1; i++ ){ ~~^~~~~~~~~~~~~~~~~~~ user.cpp:39:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1; i < A[k].length() - 1; i++ ) ~~^~~~~~~~~~~~~~~~~~~ user.cpp:41:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1; i < A[k].length() - 1; i++ ){ ~~^~~~~~~~~~~~~~~~~~~