Compilare: main.cpp: In function 'void solve()': main.cpp:71:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < M.size(); ++i) ~~^~~~~~~~~~ main.cpp: In function 'void read()': main.cpp:34:17: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ main.cpp:43:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &A[i][j]); ^ main.cpp: In function 'int main()': main.cpp:113:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("alpin.in", "r", stdin); ^ main.cpp:114:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("alpin.out", "w", stdout); ^ main.cpp: In function 'void solve()': main.cpp:67:6: warning: 'maxj' may be used uninitialized in this function [-Wmaybe-uninitialized] int maxj; ^~~~ main.cpp:66:6: warning: 'maxi' may be used uninitialized in this function [-Wmaybe-uninitialized] int maxi; ^~~~