Compilare: user.cpp: In function ‘int main()’: user.cpp:62:9: warning: unused variable ‘l’ [-Wunused-variable] int l,i,j,z,q; ^ user.cpp:59:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("collar.in","r",stdin); ^ user.cpp:60:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("collar.out","w",stdout); ^ user.cpp:65:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&N); ^ user.cpp:66:46: 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",&a[i]); ^