Compilare: user.cpp: In function ‘void solve(int)’: user.cpp:43:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1; i < A[k].length() - 1; i++ ){ ~~^~~~~~~~~~~~~~~~~~~ user.cpp:52:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1; i < A[k].length() - 1; i++ ){ ~~^~~~~~~~~~~~~~~~~~~ user.cpp:56:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 1; i < A[k].length() - 1; i++ ){ ~~^~~~~~~~~~~~~~~~~~~ user.cpp: In function ‘int main()’: user.cpp:86:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < V.size(); i++ ){ ~~^~~~~~~~~~