Compilare: user.cpp: In function ‘void form()’: user.cpp:28:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1; i<m.size(); i++) ^ user.cpp: In function ‘void solve()’: user.cpp:34:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<x.size(); i++) ^ user.cpp:36:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=m[0]; i<x[0].size(); i++) ^ user.cpp:38:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=1; i<x.size(); i++) ^ user.cpp: At global scope: user.cpp:52:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main() ^