Compilare: main.cpp: In function 'int main()': main.cpp:38:25: warning: unused variable 'diff' [-Wunused-variable] int diff=(int)v[l].r*v[l].r-dist2d-(mat[v[l].x][v[l].y]-mat[i][j])*(mat[v[l].x][v[l].y]-mat[i][j]); ^~~~ main.cpp:12:37: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] { freopen("radio.in", "r" , stdin); ^ main.cpp:13:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("radio.out", "w", stdout); ^ main.cpp:15:32: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &m, &n, &k); ^ main.cpp:18:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &mat[i][j]); ^ main.cpp:20:52: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%lf", &v[i].x, &v[i].y, &v[i].r); ^