Compilare: main.cpp: In function 'void calc_mex()': main.cpp:41:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < v[crt].size(); j++) { ~~^~~~~~~~~~~~~~~ main.cpp:47:17: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while(j < v[crt].size() - 1 && mex[v[crt][j]] == mex[v[crt][j + 1]]) ~~^~~~~~~~~~~~~~~~~~~ main.cpp: In function 'int main()': main.cpp:55:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pawns.in", "r", stdin); ^ main.cpp:56:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("pawns.out", "w", stdout); ^ main.cpp:59:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ main.cpp:61:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^ main.cpp:70:18: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &t); ^ main.cpp:74:22: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &y); ^