CF154D. Flatland Fencing [博弈论 对称 平局]

#include <iostream>
#include <cstdio>
#include <cstring>
#include <algorithm>
#include <cmath>
using namespace std;
const int N=1005;
inline int read(){
    char c=getchar();int x=0,f=1;
    while(c<‘0‘||c>‘9‘){if(c==‘-‘)f=-1; c=getchar();}
    while(c>=‘0‘&&c<=‘9‘){x=x*10+c-‘0‘; c=getchar();}
    return x*f;
}
int x1,x2,a,b,f=1;
void solve(){
    if(x1+a<=x2 && x2<=x1+b) {puts("FIRST"),printf("%d\n",x2);return;}

    if(a==0 || b==0) {puts("DRAW");return;}
    if(a<0 && b>0) {puts("DRAW");return;}
    if(a>0){
        if(x1>x2) {puts("DRAW");return;}
    }else{
        if(x1<x2) {puts("DRAW");return;}
        a=-a;b=-b;swap(a,b);f=-1;
    }
    int d=abs(x1-x2),t=d%(a+b);//printf("d %d %d\n",d,t);

    if(t==0) puts("SECOND");
    else if(a<=t&&t<=b) puts("FIRST"),printf("%d\n",x1+t*f);
    else puts("DRAW");
}
int main(){
    //freopen("in","r",stdin);
    x1=read();x2=read();a=read();b=read();
    solve();
}