C++ :

#include<iostream>
#include<iomanip>
using namespace std;
int main(){
	int a,b,c,d;
	cin>>a>>b>>c>>d;
	if(a<b){
		cout<<a;
	}else if(b<c){
		cout<<b;
	}else if(c<d){
		cout<<c;
	}else if(b<c){
		cout<<b;
	}else if(b<d){
		cout<<b;
	}else if(a<c){
		cout<<a;
	}else if(a<d){
		cout<<d;
	}
	return 0;
}

Java :

import java.util.Scanner;
public class Main
{   
	public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        int c = sc.nextInt();
        int d = sc.nextInt();
        int min = a;
        if(min>b) {
        	min=b;
        }if(min>c) {
        	min=c;
        }
        if(min>d) {
        	min=d;
        }
        System.out.println(min);
    
    }
}