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:20:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
20 | while(x < a.size() and y < b.size() and ans.size() < BLOCK_SIZE) {
| ~~^~~~~~~~~~
bitaro.cpp:20:30: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
20 | while(x < a.size() and y < b.size() and ans.size() < BLOCK_SIZE) {
| ~~^~~~~~~~~~
bitaro.cpp:21:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
21 | while(x < a.size() and vis[a[x].second]) x++;
| ~~^~~~~~~~~~
bitaro.cpp:22:17: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
22 | while(y < b.size() and vis[b[y].second]) y++;
| ~~^~~~~~~~~~
bitaro.cpp:23:14: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
23 | if(x == a.size() or y == b.size()) break;
| ~~^~~~~~~~~~~
bitaro.cpp:23:31: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
23 | if(x == a.size() or y == b.size()) break;
| ~~^~~~~~~~~~~
bitaro.cpp:32:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
32 | while(x < a.size() and ans.size() < BLOCK_SIZE)
| ~~^~~~~~~~~~
bitaro.cpp:34:13: warning: comparison of integer expressions of different signedness: 'int' and 'std::vector<std::pair<int, int> >::size_type' {aka 'long unsigned int'} [-Wsign-compare]
34 | while(y < b.size() and ans.size() < BLOCK_SIZE)
| ~~^~~~~~~~~~
bitaro.cpp: In function 'int main()':
bitaro.cpp:72:17: warning: unused variable 'ans' [-Wunused-variable]
72 | int ans = -1;
| ^~~
bitaro.cpp:44:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
44 | freopen(TASK ".inp", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~
bitaro.cpp:45:16: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
45 | freopen(TASK ".out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~