Compilare: main.cpp: In function 'void read()': main.cpp:20:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("elimin.in", "r", stdin); ^ main.cpp:21:38: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d", &n, &m, &r, &c); ^ main.cpp:24:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &val[i][j]); ^ main.cpp: In function 'void write()': main.cpp:45:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("elimin.out", "w", stdout); ^