Compilare: user.cpp: In function ‘int main()’: user.cpp:36:15: warning: unused variable ‘x’ [-Wunused-variable] int n, i, x, y, a, b, sum=0; ^ user.cpp:36:18: warning: unused variable ‘y’ [-Wunused-variable] int n, i, x, y, a, b, sum=0; ^ user.cpp:36:21: warning: unused variable ‘a’ [-Wunused-variable] int n, i, x, y, a, b, sum=0; ^ user.cpp:36:24: warning: unused variable ‘b’ [-Wunused-variable] int n, i, x, y, a, b, sum=0; ^ user.cpp:38:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp:41:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &v[i].first); ^