View Compilation Error

0_0_25014829_17830.c:7:1: error: unknown type name 'bool'
 bool check;
 ^
0_0_25014829_17830.c:8:23: error: expected ';', ',' or ')' before '&' token
 ll exgcd(ll a,ll b,ll &x,ll &y)
                       ^
0_0_25014829_17830.c: In function 'solve':
0_0_25014829_17830.c:35:8: error: 'true' undeclared (first use in this function)
  check=true;
        ^
0_0_25014829_17830.c:35:8: note: each undeclared identifier is reported only once for each function it appears in
0_0_25014829_17830.c:44:10: error: 'false' undeclared (first use in this function)
    check=false;
          ^