C :

#include<stdio.h>

int x,y,z,n;
int a[500],b[500],c[500];

void input_data()
{
    scanf("%d %d",&x,&y);
    if (x > y)
        {
            z = x;x = y;y = z;
        }
    n = y - x + 1;
}

void get_ans()
{
    memset(a,0,sizeof(a));
    memset(b,0,sizeof(b));
    memset(c,0,sizeof(c));
    int la = 1,lb = 1,lc;
    a[1] = 1;b[1] = 1;
    if ( n == 1)
        {
            printf("1");
            return;
        }
    if (n == 2)
        {
            printf("1");
            return;
        }
    for (int i = 3;i <=n;i++)
        {
            int l;
            if (lb > la)
                l = lb;
                    else
                        l = la;
            int x = 0;
            for (int j = 1;j <= l;j++)
                {
                    c[j] = a[j] + b[j] + x;
                    x = c[j] / 10;
                    c[j] = c[j] % 10;
                }
            while (x > 0)
                {
                    l++;
                    c[l] += x;
                    x = c[l] / 10;
                    c[l] = c[l] % 10;
                }
            lc = l;
            for (int j = 1;j <= lb;j++)
                a[j] = b[j];
            la = lb;
            for (int j = 1;j <= lc;j++)
                b[j] = c[j];
            lb = lc;
        }
    for (int j = lc;j >= 1;j--)
        printf("%d",c[j]);
}

int main()
{
    input_data();
    get_ans();
    return 0;
}

C++ :

#include <bits/stdc++.h>
using namespace std;

//高精度求和 
string num(string s1,string s2){
	string r = ""; 
	int i,len;//len存较长的长度 
	int a[250] = {0},b[250] = {0},c[250] = {0};
	//第一步：将2个字符数组逆序存入2个整数数组
	//s1 = "12345";
	for(i = 0;i < s1.size();i++){
		//0->s1.size()-1  1->s1.size()-2
		a[s1.size()-i-1] = s1[i] - '0';
	} 
	
	for(i = 0;i < s2.size();i++){
		b[s2.size()-i-1] = s2[i] - '0';
	}
	
    //第二步：逐位相加，逐位进位
    //int len = s1.size() > s2.size()?s1.size():s2.size();//三目运算符，替代if else 
	len = s1.size();
	if(s2.size() > s1.size()){
		len = s2.size();
	} 
	
	//加 
	for(i = 0;i < len;i++){
		c[i] = a[i] + b[i];
	}
	//进位
	for(i = 0;i < len;i++){
		if(c[i] >= 10){
			c[i+1] = c[i+1] + c[i] / 10;
			c[i] = c[i] % 10;
		}
	} 
	
	//第三步：逆序输出
	if(c[len] != 0){
		len++;
	} 
	
	for(i = len - 1;i>=0;i--){
		r = r + (char)(c[i] + 48);
	}
	return r;
}

int main(){
	long long m,n,x,i;
	cin>>m>>n;
	x = n - m;
	string t1,t2,t;
	t1 = "1";
	t2 = "2";
	for(i = 3;i <= x;i++){
		t = num(t1,t2);
//		cout<<i<<" "<<t<<endl;
		t1 = t2;
		t2 = t;
	}
	
	cout<<t2<<endl;
//	cout<<LONG_LONG_MAX<<endl;
    return 0;
}

Python :

sr=input().split()
M=int(sr[0])
N=int(sr[1])
a=[]
a.append(0)
for i in range(1,N+1):
    if(i==1):
        a.append(1)
    elif(i==2):
        a.append(1)
    else:
        a.append(a[i-2]+a[i-1])
print(a[N-M+1])