Compilare: user.cpp: In function ‘void read()’: user.cpp:76:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int k = 0; k < r[i*n+j].size(); ++k) ^ user.cpp:23:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mxl.in", "r", stdin); ^ user.cpp:24:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &n, &m); ^ user.cpp:28:37: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d%c", &x, &y, &q); ^ user.cpp:30:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%c", &q); ^ user.cpp:34:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%c", &q); ^ user.cpp:44:35: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c", &q); ^ user.cpp:55:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%c", &q); ^ user.cpp: In function ‘void write()’: user.cpp:101:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mxl.out", "w", stdout); ^