/in/foo.cc:4:14: error: expected ')' before ';' token
 int gcd(int a;int b)
              ^
/in/foo.cc:4:20: error: expected initializer before ')' token
 int gcd(int a;int b)
                    ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:16:24: error: too many arguments to function 'int gcd(int)'
    if(t%i==0&&gcd(i,t%i)==1)
                        ^
/in/foo.cc:4:5: note: declared here
 int gcd(int a;int b)
     ^~~