Eroare de compilare: main.cpp: In function 'int main()': main.cpp:20:50: error: 'abs' was not declared in this scope if(k - i == abs(st[k] - st[i]) || st[i] == st[k]) ^ main.cpp:20:50: note: suggested alternative: In file included from main.cpp:2:0: /usr/include/c++/6/cmath:103:5: note: 'std::abs' abs(_Tp __x) ^~~ main.cpp:7:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("damesah.in", "r", stdin); ^ main.cpp:8:40: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("damesah.out", "w", stdout); ^ main.cpp:9:20: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ Non zero exit status: 1