Compilare: main.cpp: In function 'int main()': main.cpp:14:15: warning: unused variable 'a' [-Wunused-variable] long long a, b, sum = 0; ^ main.cpp:14:18: warning: unused variable 'b' [-Wunused-variable] long long a, b, sum = 0; ^ main.cpp:11:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.in", "r", stdin); ^ main.cpp:12:39: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("trapez.out", "w", stdout); ^ main.cpp:15:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ main.cpp:17:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &x[i], &y[i]); ^