what's wrong in my code, please give me some test

#include <iostream>
#include <vector>
#include <string>
#include <map>
using namespace std;

map<string,string>functions;
map<string,string>variables;



int main(){
    int count_function, count_variable,i,j;
    string line,s1,s2,s, type;
    cin >> count_function;
    for(i = 0; i < count_function; i ++){
        cin >> s1;
        while(cin >> s){
            if(s == ":") break;
            s1 = s1 + " " + s;
        }
        cin >> s2;
        functions[s1] = s2;
    }

    cin >> count_variable;

    vector<string>variable;
    vector<string>types;

    for(i = 0; i < count_variable; i ++){
        cin >> type >> s >> s1 >> s1;
        while(s1[s1.size() - 1] != ')'){
            cin >> s2;
            s1 = s1 + " " + s2;
        }
        if(variables.find(s) == variables.end()){

            s2 = "";
            j = 0;
            while(s1[j] != '(') s2 += s1[j++];  s2 += '('; j ++;
            while(s1[j] != ')'){
                line = "";
                while(s1[j] != ',' && s1[j] != ')') line += s1[j++];
                if(variables.find(line) == variables.end()){
                    cout << "Error on line " << i + 1 << ": " << "Unknown variable" << endl;
                    return 0;
                }
                s2 += variables[line];
                if(s1[j] == ','){
                    s2 += ", ";
                    j += 2;
                }
            }
            s2 += ')';

            if(functions.find(s2) == functions.end()){
                cout << "Error on line " << i + 1 << ": " << "No such function" << endl;
                return 0;
            }

            s2 = functions[s2];

            if(type == "auto"){
                variable.push_back(s);
                types.push_back(s2);
                type = s2;
            }
            if(type != s2){
                cout << "Error on line " << i + 1 << ": " << "Invalid initialization" << endl;
                return 0;
            }
            variables[s] = s2;
        }else{
            cout << "Error on line 2: Double declaration" << endl;
            return 0;
        }
    }
    for(i = 0; i < types.size(); i ++) cout << variable[i] << " : " << types[i] << endl;
    return 0;
}