Compilare: user.cpp: In function ‘void back(int)’: user.cpp:8:14: warning: unused variable ‘c1’ [-Wunused-variable] {int c1,c2,x,p; ^ user.cpp:8:17: warning: unused variable ‘c2’ [-Wunused-variable] {int c1,c2,x,p; ^ user.cpp:8:20: warning: unused variable ‘x’ [-Wunused-variable] {int c1,c2,x,p; ^ user.cpp: In function ‘int main()’: user.cpp:49:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] {freopen ("eqs.in","r",stdin); ^ user.cpp:50:31: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("eqs.out","w",stdout); ^ user.cpp:52:50: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d%d%d",&v[1],&v[2],&v[3],&v[4],&v[5]); ^