Compilare: user.cpp: In function ‘int main()’: user.cpp:32:33: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d %d", &n, &k); ^ user.cpp:36:99: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%lld %lld %lld %lld", &pct[2*i].x, &pct[2*i].y, &pct[2*i+1].x, &pct[2*i+1].y); ^ user.cpp:67:54: warning: ‘prev’ may be used uninitialized in this function [-Wmaybe-uninitialized] s += (v[i+1] - v[i]) * (pct[j].x - prev); ^