Compilare: main.cpp:4:0: warning: "M_PI" redefined #define M_PI 3.1415926535 In file included from /usr/include/c++/6/cmath:45:0, from main.cpp:2: /usr/include/math.h:418:0: note: this is the location of the previous definition # define M_PI 3.14159265358979323846 /* pi */ main.cpp: In function 'int main()': main.cpp:8:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("expand.in", "r", stdin); ^ main.cpp:9:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("expand.out", "w" ,stdout); ^ main.cpp:11:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ main.cpp:12:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &r); ^ main.cpp:14:34: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%lf%lf", &x[i], &y[i]); ^