Compilare: user.cpp: In function ‘int main()’: user.cpp:9:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("aria.in","r",stdin); ^ user.cpp:10:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("aria.out","w",stdout); ^ user.cpp:12:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:14:40: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&v[i][1],&v[i][2]); ^ user.cpp:16:21: warning: array subscript is above array bounds [-Warray-bounds] v[n+1][2]=v[1][2]; ^ user.cpp:16:13: warning: array subscript is above array bounds [-Warray-bounds] v[n+1][2]=v[1][2]; ^ user.cpp:18:36: warning: array subscript is above array bounds [-Warray-bounds] s=s+(0-v[i][1])*(0-v[i+1][2])-(0-v[i+1][1])*(0-v[i][2]); ^ user.cpp:18:62: warning: array subscript is above array bounds [-Warray-bounds] s=s+(0-v[i][1])*(0-v[i+1][2])-(0-v[i+1][1])*(0-v[i][2]); ^