bitaro.cpp: In function 'std::vector<std::pair<int, int> > merge_vector(std::vector<std::pair<int, int> >, std::vector<std::pair<int, int> >)':
bitaro.cpp:22:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
22 | while(x < a.size() and y < b.size() and ans.size() < BLOCK_SIZE) {
| ~~^~~~~~~~~~
bitaro.cpp:22:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
22 | while(x < a.size() and y < b.size() and ans.size() < BLOCK_SIZE) {
| ~~^~~~~~~~~~
bitaro.cpp:23:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
23 | while(x < a.size() and vis[a[x].second]) x++;
| ~~^~~~~~~~~~
bitaro.cpp:24:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
24 | while(y < b.size() and vis[b[y].second]) y++;
| ~~^~~~~~~~~~
bitaro.cpp:25:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
25 | if(x == a.size() or y == b.size()) break;
| ~~^~~~~~~~~~~
bitaro.cpp:25:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
25 | if(x == a.size() or y == b.size()) break;
| ~~^~~~~~~~~~~
bitaro.cpp:40:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
40 | while(x < a.size() and ans.size() < BLOCK_SIZE) {
| ~~^~~~~~~~~~
bitaro.cpp:47:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
47 | while(y < b.size() and ans.size() < BLOCK_SIZE) {
| ~~^~~~~~~~~~
bitaro.cpp: In function 'int main()':
bitaro.cpp:62:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
62 | freopen(TASK ".inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
bitaro.cpp:63:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
63 | freopen(TASK ".out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~