Compilare: main.cpp: In function 'int main()': main.cpp:20:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (size_t i = 1; i <= n; i++) ~~^~~~ main.cpp:24:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (size_t i = 1; i <= m; i++) ~~^~~~ main.cpp:30:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (size_t i = 1; i <= n; i++) ~~^~~~ main.cpp:32:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (size_t j = 1; j <= m; j++) ~~^~~~