Compilare: user.cpp: In function ‘int query(int, int)’: user.cpp:42:81: warning: operation on ‘dr’ may be undefined [-Wsequence-point] sum2.f =sum2.f*pw[arb[--dr].s]+arb[dr].f,sum2.f%=p,sum2.s+=arb[dr].s; ^ user.cpp:28:9: warning: unused variable ‘sum’ [-Wunused-variable] int sum = 0; ^ user.cpp: In function ‘int main()’: user.cpp:48:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rest.in","r",stdin); ^ user.cpp:49:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("rest.out","w",stdout); ^ user.cpp:50:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d\n",&n,&b,&p); ^ user.cpp:52:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &arb[i+n].f); ^ user.cpp:55:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n", &m); ^ user.cpp:58:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &instr,&x,&y); ^