rack.cpp: In function 'int main()':
rack.cpp:48:21: warning: left operand of comma operator has no effect [-Wunused-value]
48 | val=(val+pw[2, n-1])%MOD;
| ^
rack.cpp:51:21: warning: left operand of comma operator has no effect [-Wunused-value]
51 | val=(val+pw[2, n-2])%MOD;
| ^
rack.cpp:54:21: warning: left operand of comma operator has no effect [-Wunused-value]
54 | val=(val+pw[2, n-2]%MOD+pw[2, n-1])%MOD;
| ^
rack.cpp:54:36: warning: left operand of comma operator has no effect [-Wunused-value]
54 | val=(val+pw[2, n-2]%MOD+pw[2, n-1])%MOD;
| ^
rack.cpp: In function 'void setIO(std::string)':
rack.cpp:31:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
31 | freopen((s+".in").c_str(),"r",stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~
rack.cpp:32:10: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
32 | freopen((s+".out").c_str(),"w",stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~