kangaroo.cpp: In function 'int main()':
kangaroo.cpp:16:16: warning: unused variable 'j' [-Wunused-variable]
16 | ll n,a,b,i,j,per=0;
| ^
kangaroo.cpp:14:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
14 | freopen("kangaroo.in", "r", stdin);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~
kangaroo.cpp:15:12: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)' declared with attribute 'warn_unused_result' [-Wunused-result]
15 | freopen("kangaroo.out", "w", stdout);
| ~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~