Compilare: user.cpp: In function ‘int main()’: user.cpp:20:11: warning: unused variable ‘j’ [-Wunused-variable] int i,j,a,b; ^ user.cpp:22:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tribes.in","r",stdin); ^ user.cpp:23:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("tribes.out","w",stdout); ^ user.cpp:24:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&n,&m1,&k); ^ user.cpp:25:45: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i=1;i<=n;i++) { scanf("%d",&trib[i]); sf[i][trib[i]]=1; } ^ user.cpp:29:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&a,&b); ^