poj1061 2010.2.17

poj1061 2010.2.17

#include <iostream>using namespace std;__int64 x,y,m,n,l;__int64 modularLinearEquation(__int64 a,__int64 b,__int64 n);__int64 extEuclid(__int64 a, __int64 b);int main(void){__int64 s;scanf("%I64d",&x);scanf("%I64d",&y);scanf("%I64d",&m);scanf("%I64d",&n);scanf("%I64d",&l);s=modularLinearEquation((n-m+l)%l,(x-y+l)%l,l);if (s<0)printf("Impossible\n");elseprintf("%I64d\n",s);return 0;}__int64 modularLinearEquation(__int64 a,__int64 b,__int64 n){__int64 d,result;result=-1;d=extEuclid(a,n);if (b%d!=0) return result;x=x*(b/d);x=(x%(n/d)+n/d)%(n/d);result=x;return result;}__int64 extEuclid(__int64 a, __int64 b){__int64 r,t;    if (b==0){  x=1;y=0;return a;}    r=extEuclid(b,a%b);t=x;      x=y; y=t-a/b*y;    return r;}