Compilare: main.cpp: In function 'int32_t main()': main.cpp:248:7: warning: unused variable 'aux' [-Wunused-variable] int aux = mat[x2][y2] - mat[x2][y1 - 1] - mat[x1 - 1][y2] + mat[x1 - 1][y1 - 1]; ^~~ main.cpp:197:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen(PROB_NAME".out", "w", stdout); ^ main.cpp:199:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen(PROB_NAME".in", "r", stdin); ^