C :

#include<stdio.h>
void main()
{
    int a, n, m, x;
    scanf("%d%d%d%d",&a,&n,&m,&x);
    int f[24];
    f[1] = 1;
    f[2] = 1;
    for(int i = 3; i < 24; i++)
    {
        f[i] = f[i-1] + f[i-2];
    }
    printf("%d\n",(f[x-2]+1)*a+(f[x-1]-1)*(m-(f[n-3]+1)*a)/(f[n-2]-1));
} 

C++ :

#include<stdio.h>
int main()
{
	int a,n,m,x,k,i,b[100],c[100],d[100];
	while(scanf("%d%d%d%d",&a,&n,&m,&x)!=EOF)
	{
		if(n<=3)
		{
			printf("%d\n",a);
			continue;
		}
		if(x==n)
		{
			printf("0\n");
			continue;
		}
		k=1;
		b[1]=a,b[2]=a;
		c[1]=a,d[1]=0;
		b[n-1]=0;
		while(b[n-1]!=m)
		{
		
			c[2]=k,d[2]=k;
			for(i=3;i<=n-1;i++)
			{
				c[i]=c[i-1]+c[i-2];
				d[i]=c[i-1];
				b[i]=b[i-1]+c[i]-d[i];
			}
			k++;
		}
		printf("%d\n",b[x]);
	}
	return 0;
}

Pascal :

var
 a,n,x,m,s,i:longint;
 a1:array[1..2,1..20] of longint;
 a2:array[1..2,1..20] of longint;
 a3:array[1..2,1..20] of int64;
begin
 readln(a,n,m,x);
 a1[1,1]:=1;a1[1,2]:=0; a1[2,1]:=0;a1[2,2]:=1;
 a2[1,1]:=0;a2[1,2]:=0; a2[2,1]:=0;a2[2,2]:=1;
 a3[1,1]:=1;a3[1,2]:=1;
  for i:=3 to 20 do
   begin
   a1[1,i]:=a1[1,i-1]+a1[1,i-2];
   a1[2,i]:=a1[2,i-1]+a1[2,i-2];
   a2[1,i]:=a1[1,i-1];
   a2[2,i]:=a1[2,i-1];
   a3[1,i]:=a3[1,i-1]+a1[1,i]-a2[1,i];
   a3[2,i]:=a3[2,i-1]+a1[2,i]-a2[2,i];
   end;
  s:=(m-a3[1,n-1]*a) div a3[2,n-1];
  writeln(a3[1,x]*a+a3[2,x]*s);
end.

Python :

# coding=utf-8
#a,n,m,x=5,7,32,4
a,n,m,x=map(int,input().split())
ls1=[[1,0],[1,0],[2,0]]
ls2=[[1,0],[0,1],[1,1]]
for i in range(3,n):
	an2=ls2[i-1][0]+ls2[i-2][0]
	bn2=ls2[i-1][1]+ls2[i-2][1]
	ls2.append([an2,bn2])
	an1=ls1[i-1][0]+ls2[i-2][0]
	bn1=ls1[i-1][1]+ls2[i-2][1]
	ls1.append([an1,bn1])
b=(m-ls1[n-2][0]*a)//ls1[n-2][1]
print(ls1[x-1][0]*a+ls1[x-1][1]*b)