Compilare: user.cpp: In function ‘void solve(int, int, int)’: user.cpp:40:15: warning: unused variable ‘c’ [-Wunused-variable] int sens2,c; ^ user.cpp: In function ‘int main()’: user.cpp:97:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("spider.in","r",stdin); ^ user.cpp:98:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("spider.out","w",stdout); ^ user.cpp:99:27: 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:102:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d ",&M[i][j]); ^