#include <bits/stdc++.h>
            #include<iostream>
            #include<cstdio>
            #include<vector>
            #include<queue>
            #include<map>
            #include<cstring>
            #include<string>
            #include <math.h>
            #include<algorithm>
        //    #include <boost/multiprecision/cpp_int.hpp>
            #include<functional>
     #define int long long
            #define mod  1000000007
            #define pa pair<int,int>
            #define ll long long
            #define pal pair<double,int>
            #define ppa pair<int,pa>
            #define ssa pair<string,int>
            #define  mp make_pair
            #define  pb push_back
            #define EPS (1e-10)
            #define equals(a,b) (fabs((a)-(b))<EPS)
     
            using namespace std;
     //priority_queue<int, vector<int>, greater<int> > que;
            class Point{
            	public:
            	double x,y;
            	Point(double x=0,double y=0):x(x),y(y) {}
            	Point operator + (Point p) {return Point(x+p.x,y+p.y);}
            	Point operator - (Point p) {return Point(x-p.x,y-p.y);}
            	Point operator * (double a) {return Point(x*a,y*a);}
            	Point operator / (double a) {return Point(x/a,y/a);}
            	double absv() {return sqrt(norm());}
            	double norm() {return x*x+y*y;}
            	bool operator < (const Point &p) const{
            		return x != p.x ? x<p.x: y<p.y;
            	}
            	bool operator == (const Point &p) const{
            		return fabs(x-p.x)<EPS && fabs(y-p.y)<EPS;
            	}
            };
            typedef Point Vector;
     
            struct Segment{
            Point p1,p2;
            };
     
        double hen(Vector a){
        if(fabs(a.x)<EPS && a.y>0) return acos(0);
        else if(fabs(a.x)<EPS && a.y<0) return 3*acos(0);
        else if(fabs(a.y)<EPS && a.x<0) return 2*acos(0);
        else if(fabs(a.y)<EPS && a.x>0) return 0.0;
        else if(a.y>0) return acos(a.x/a.absv());
        else return 2*acos(0)+acos(-a.x/a.absv());
     
        }
     
string itos( int i ) {
ostringstream s ;
s << i ;
return s.str() ;
}

int gcd(int v,int b){
	if(v>b) return gcd(b,v);
	if(v==b) return b;
	if(b%v==0) return v;
	return gcd(v,b%v);
}
            double dot(Vector a,Vector b){
            	return a.x*b.x+a.y*b.y;
            }
            double cross(Vector a,Vector b){
            	return a.x*b.y-a.y*b.x;
            }
        
double distans(double x1,double y1,double x2,double y2){
	double rr=(x1-x2)*(x1-x2)+(y1-y2)*(y1-y2);
	return sqrt(rr);
	
}
 
int beki(int a, int r){
	if(r==0)return 1;
	if(r==1) return a%mod; 
	if(r%2==1){
		int y=beki(a,r-1);
		return(y*a)%mod;
		
	}
	int yy=beki(a,r/2);
	return (yy*yy)%mod;
}
 
 int inf=mod*2;
 /*
 int kai[100000];
 int inv[100000];
int memo[1004][1004]={0};
*/
int n,m,k;
            //----------------kokomade tenpure------------
int a[110][110];
void yoko(int r,int d){
	int e=a[r][1];
	for(int i=2;i<=d;i++) a[r][i-1]=a[r][i];
	a[r][d]=e;
	return;
}

void tate(int r,int d){
//	cout<<r<<" "<<d<<endl;
	int e=a[1][r];
	for(int i=2;i<=d;i++) a[i-1][r]=a[i][r];
	a[d][r]=e;
	return;
}

    signed  main(){
string s;
    	cin>>s;
    	int b,c,l=s.length();
    	for(int i=0;i<l;i++) if(s[i]=='Z') c=i;
    	for(int i=l-1;i>=0;i--) if(s[i]=='A') b=i;
    	cout<<1+c-b<<endl;
    	return 0;
    }

    //printf("%d %.10f %.10f\n",i,xx/ri,yy/ri);

Measured memory_bytes: 640