View Compilation Error

0_0_27564440_23757.cpp: In function 'int exgcd(int, int, int&, int&)':
0_0_27564440_23757.cpp:14:21: error: invalid initialization of reference of type 'int&' from expression of type 'long long int'
  d=exgcd(b%a,a,tx,ty);
                     ^
0_0_27564440_23757.cpp:9:5: note: in passing argument 3 of 'int exgcd(int, int, int&, int&)'
 int exgcd(int a,int b,int &x,int &y){
     ^