Compilare: user.cpp: In function ‘int main()’: user.cpp:41:13: warning: unused variable ‘a’ [-Wunused-variable] int n,i,a,b,c,e; ^ user.cpp:41:15: warning: unused variable ‘b’ [-Wunused-variable] int n,i,a,b,c,e; ^ user.cpp:41:17: warning: unused variable ‘c’ [-Wunused-variable] int n,i,a,b,c,e; ^ user.cpp:41:19: warning: unused variable ‘e’ [-Wunused-variable] int n,i,a,b,c,e; ^ user.cpp: In function ‘int solve(int)’: user.cpp:39:1: warning: control reaches end of non-void function [-Wreturn-type] } ^ user.cpp: In function ‘int main()’: user.cpp:42:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mergesort.in","r",stdin); ^ user.cpp:43:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mergesort.out","w",stdout); ^ user.cpp:44:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^