Eroare de compilare: main.cpp:22:25: error: ISO C++ forbids declaration of 'operator<' with no type [-fpermissive] operator < (pii a, pii b) { ^ main.cpp: In function 'int main()': main.cpp:120:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("fpwl.in", "r", stdin); ^ main.cpp:121:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("fpwl.out", "w", stdout); ^ main.cpp:123:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &n, &k); ^ main.cpp:125:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%d", &v[i]); ^ main.cpp:128:15: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("\n"); ^ main.cpp:131:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf ("%c ", &c); ^ Non zero exit status: 1