Compilare: user.cpp: In function ‘int main()’: user.cpp:30:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0 ; i < v[0].length() ; i++) { ^ user.cpp:32:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0 ; j < 60 && j + i < v[0].length() ; j++) { ^ user.cpp:56:42: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0 ; i < v[k - 1].length() ; i++) { ^ user.cpp:58:60: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j = 0 ; j < 60 && j + i < v[k - 1].length() ; j++) { ^