Compilare: user.cpp: In function ‘int main()’: user.cpp:7:18: warning: unused variable ‘x’ [-Wunused-variable] int n, m, i, j, x, nr = 0; ^ user.cpp:12:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("submat.in", "r", stdin); ^ user.cpp:13:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("submat.out", "w", stdout); ^ user.cpp:14:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d\n", &n, &m); ^ user.cpp:16:10: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); sw = 1; ^ /tmp/ccNIGfqd.o: In function `main': user.cpp:(.text.startup+0xa9): warning: the `gets' function is dangerous and should not be used.